I’m not running a pressure reducer at all. Whatever the line/tank pressure is, that’s what hits the nozzles. I run 80-100psi.
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Ah, you told me that before and I keep forgetting 
Of course, the downside to that is the mist quality (droplet size) and flow rate will be constantly changing while the pressure is changing. You will get smaller droplets, but higher flow rates at 100 PSI, and larger droplets, but lower flow rate at 80 PSI. It might be a good idea to flow test at both pressures just to see how big the difference is. You might need to take an average of something when it comes to calculations. I have no idea what the difference might be - Iv done all my testing at a constant pressure.
On the other hand, that may not really be that much of an issue - especially in your case. At the flow rates you were running before, your pump must cycle a lot more often. Faster cycle times should tend to even things out I would think. As far as I have heard, those pumps are pretty bullet proof, so higher cycle rates shouldnt be an issue there. Plus, the smaller nozzle openings your using may not be as sensitive to pressure changes.
Feel free to ignore all my rambling - Im half baked
I was considering switching to a diaphragm type pump at some point to reduce noise, but now Im vaguely remembering the normal 5000/8000 series wont go above about 120 PSI? I cant remember now, but I was wanting higher max pressure so I could have a larger differential between the min/max pressure so I could lower the cycle rate on the pumps.
That might be worth considering if you are subject to power outages very often. You can run the solenoids and timer for many hours from a small 12 volt battery, but your pump will need a much bigger back up power system.
That is something I have been intending to do, but have not gotten around to yet. I have a battery, wiring, and switches to do it, but no automatic relay. I would have to wire it all up using flashlights if the power were to go out suddenly
Im not toooo worried about it even though I probably should be. Our power hasnt been off for more than a few minutes in three or four years at least.
In other news - it occurs to me I have mostly been posting BAD NEWS items. So, I want to shout out another big thanks to @Northern_Loki for the donated RO filters and @MicroDoser for additionally nudging me to make the switch to RO.
Since the switch, I have had zero zombie algae apocalypse ‘brown outs’ on the roots like I had earlier. I am sure its the RO water mostly, but the UV light is probably helping as well. I know its killing something in the rez anyway.
I cant decide if this next thing is good news or not, but the roots are growing really well - a bit too well. Im loosing two more nozzles to the roots, and the duct tape roots are getting out of control. Im going to have to get in there and do some root trimming again and move at least two nozzles again. The top of the chamber is so full, I can no longer get my hand anywhere near the back 2/3 of the chamber or into the bottom section - unless Im willing to crush a lot of roots. So, no more ‘root tour’ videos. Its getting more difficult to even get regular pics of the roots for lack of room. Im guessing Im somewhere close to or over 30 gallons of roots at this point. The lower mat is in full contact with the umbrella in several places as well.
As far as I can tell, this isnt a major issue at this point. I dont smell any root rot and cant see any drying out anywhere. I can only assume the roots are wicking moisture from where its being sprayed to where its not - at least enough to keep things going. At least thats my hope. I cant see or feel anything in 2/3rds of the chamber though.
Im hoping I can get this root mass out in one piece and get some decent pics of it.
In the mean time, here are a few pics as best as I can get.
I just noticed there is a big ass tap root growing UP into the duct tape!! Now Im starting to worry about the strength of my root chamber lid! The lid is just 1" thick foam circle 24" in diameter with a single piece is aluminum bar as reinforcement. If that root breaks the bond between the foam and aluminum bar, the whole plant could drop into the chamber!!
I decided to trim some roots back up top to free up one nozzle, but I stopped. I would need to trim out at least a gallon or more to do any good, and Id rather not do that - yet. Plus, Im worried about the extra damage Im doing by handling and any cut pieces that drop in the chamber could be a source of rot.
Im going to make up some root cream’ and see if it works on my arthritic joints.
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I topped off the rez last night. Unless I siphon it out, there is always about 3 gallons left in the rez when it reaches the drain port.
This time when I topped off, I did NOT drain all that out. I just added about 6 gallons of RO water and enough AN nutes to get back to EC 1.0. PH was holding last night at 5.6.
This morning it was up to 5.7 and tonight it was up to 5.9.
So - two things:
- running these nute below the recommended concentration is not working nearly as well as far as buffering the PH. If I do the recommended dose, the EC runs in the 1.5-1.7 range - and I got a lot of tip burn when I did that. BUT - the PH holds for two full days.
- Adding to old nutes in the rez that have lost their buffering action, accelerates the PH rise.
I am less and less impressed with these AN nutes over Mega Crop - especially for the cost difference. I got my sample of MC v2 a few days ago. I think I will switch back next time I top off and see how it does.
Oh, i ordered 1 quart of 85% Phosphoric acid to try instead of the sulfuric I have been using. Im really eager to see if using a ‘weak’ acid works better than a ‘strong’ one.
I diluted it 4 to one, but that ended up a lot stronger than my sulfuric or my old GH PH Down. That meant I shot the PH down to 4.9 with the first small addition. I decided that was too low, so I added some Potassium Hydroxide PH Up.
So, I have confused the issue by adding a strong base and a weak acid - which may have some buffering action.
Either way, it will be interesting to see if there is any change in the PH rise rate.
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Is that a thing that works? I am starting with that, my family on my mother’s side get crippling multiple joint arthritis around 50-60…
Luckily, I have access to plenty of cannabis roots, hehe. I will have a look at one of the tincture and cream threads.
Yeah, the 85% is pretty effective at lowering PH. In my 100l tank, using tap water, it takes about 15ml. Using RO it takes much less. I dilute it 1:10 before I dose with it, makes it much easier to hit the target.
Sounds like you are hitting the same problems I had with my system. It is so good at allowing root growth that the timings I did before regarding veg time etc were far too long and the roots ended up far too large, to the detriment of the plants.
I ended up (after about 3 years trying to tame a new, very vigorous clone) settling at 8-10 days veg then straight into flower. Any more than that and by mid-flower, the roots were far too large and leaks happened where the roots were just filling the gutter and nutrient solution was flowing over the sides.
In your case, I would worry about getting a place in the middle of the roots which is not getting sprayed. Maybe a nozzle right at the stalk at the top for some Reagan-era style trickle down?
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Haha no worries, sometimes I have to talk (type) something out before my brain reaches a conclusion too.
Like you said, the Aquatec pump I am using is pretty bulletproof. There are plenty of people running full RO systems and HPA setups w/ no accumulator using this pump with very low failure rates. These things are good for 30k hours of continuous usage and can pump up to 160 psi, plus I have a backup just in case.
I had thought about a pressure reducer to standardize the flow, but when testing I noticed there’s very little (if any) difference w/ the nozzles between the top and bottom pressures. Like you said it could be my nozzle orifice.
I live in the middle of nowhere, so our power goes out constantly. In fact, it went out twice last night. Luckily I have this…
This is the point I was at last time where I started to freak out due to dry areas in the root zone. It’s also why I added the secondary E&F feeding system for the lower portion. It’ll be really interesting to see what the roots look like w/ HPA only after getting so big.
Yikes. Another one of my fears right there. I struggled to figure out how to build the “lid” – strong enough to support the plant above, the roots hanging below, and still be safe from chemicals for them. I ended up with 3/4" MDF coated in pond shield because I knew it could handle whatever grew above it and the pond shield is safe for fish/plants without leeching any bad stuff. (Flex Seal will kill fish if used to line a pond, so I didn’t want to use anything like that exposed to my plant roots.)
The roots are looking good though! Getting to the really exciting part now!
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I think this is where it starts. Earlier in the thread they also mentioned that it can help with nuropathy. I have diabetic neuropathy, so Im interested for that reason too.
Yeah, I ended up diluting it another 25% and thats better, but still kind of strong.
I suspect this is what Im going to have to do as well - much shorter veg time. On the other hand, Im seeing no real problems with the over sized root mass - so far. It will depend on how things end up over the next 3 weeks or so till harvest.
Im may try two plants next time and let the roots just mix together and see what happens. Im not sure that will solve the problem though. If it takes 30 days of veg to fill a screen with a single plant, then it should only take 15 days with two plants - BUT - two plants have twice as much root volume, so I dont see that as a real help. Plus, the first few days of veg dont really do much, so you cant really cut back that much if you need to fill a scrog screen - can you?
Yeah, that was a concern a while back when I lost the first nozzle. Thats partly why I moved them to the top of the rez - I figured the water could more easily trickle down than it could wick up from below.
I cut into the root mass a good bit trimming some of it back, and the inside looks fine to me. No fuzzies, or I should say the fuzzies go away the deeper you go into the root mass. Way inside, there is just no room. The roots are packed in pretty tightly just a couple of inches in… But, they look healthy to me as far inside as I can see.
Wont know for sure until I can get the whole thing out and take a good look.
LOL yeah, thats me sometimes for sure!
They will do 160 psi? I thought they topped out at around 130. I didnt want to run it at max rating, so thats why I decided not to switch over from the solenoid pumps. If they can do 160, then it should be safe enough to run them at 130 or so.
After our last talk about the pressure switch drifting, I realized why it is so noisy and probably why the values seem to drift at times. Im pretty sure its the pressure spikes from the solenoid pumps.
Once the solenoid pump switches ON, they are a bit noisy all by themselves. However, when the pressure gets back up close tot he cut off point, the pressure switch starts to vibrate noisily maybe a minute before cut off.
I just looked at it closely while it was doing that and I can feel that the vibration rate at the switch matches the vibration rate of the pumps. Im pretty sure the pump spikes are triggering the switch to momentarily cut power on the surges, then it kicks back on when the pressure lags between pulses.
I went ahead and ordered a pressure snubber to see if Im right. If this is what is going on, it cant be good for the switch to be turning on/off 60 times a second or so like that. Im sure it will reduce its life expectancy if nothing else.
In addition to the snubber, I have all the other parts picked out to build the Arduino timer/relay setup, but Im going to have to wait on that until after the harvest. I have several things I will need to replace or re-build before the next grow, and those need to be handled first budget wise. The arduino stuff will be a very nice up-grade, but itsnt as critical as re-building lids, and replacing algae contaminated plumbing and adding more nozzles.
Yeah, as long as you have consistent flow rates and hang time between upper and lower pressures, then dont see any problem.
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Im not seeing anything like that - so far. Of course, I cant see most of the roots in the chamber at all any more, so wont know for sure until after I can do a postmortem. My fingers are staying crossed though!
The mat that I ended up with on the floor of the chamber seems to be doing much the same thing you are with your e/f setup. They seem happy enough with the left over drips from up above plus the extra they now get from the added lower nozzle.
I will look into that pond shield stuff. I dont see any sagging so far in the foam lid, but those roots have to be doing damage. Some 3/4 MDF just might be strong enough
Some up-dates.
Plants and roots still look good, but Im not impressed with the amount of trichomes for this stage. Im at 5+ weeks of 12/12 and I had more trics on previous grows I think. Pics later.
Changing over to the weak Phosphoric acid - may - have made a very slight improvement in the rate of increase of the PH - maybe. If so, it wasnt much of a change. The Ph is still going up at essentially the same rate as before, or maybe a tad slower. For sure that was not any kind of ‘fix’, so probably not a problem that needed fixing.
Next time I re-fill, I will try @MicroDoser s trick with the strong base, but more of it. I almost did it this this last time by accident time with Advanced nutes, but not to the level he does.
In the mean time, I drained the rez, flushed the system and re-filled with Mega Crop v2. I want to see how it handles the RO + UV thing as well as how much better the new buffering is compared to Advanced Nutes.
I did NOT do anything with the PH Down/PH Up mixing this time. Just a straight re-fill with RO water.
I screwed up and added my usual dose of CalMag - 1 ml/gallon - by mistake, but did not do any PH Up/Down pre-treating of the RO. I wanted to try it without any extra calmag because they said they increased the amount in the mix. Next time… This new CalMag (no extra nitrogen) doesnt add much at all to the EC, but it does lower the PH - which is the opposite of how the GH CalMag did for me. Not sure if I like that or not, so I probably will switch back to GH CalMag next time I need some.
With the calmag and just Mega Crop v2, the initial PH is 5.5 at an EC of 1.0. We will see how this does…
I just checked all around the UV light in the rez, and I cant feel any change in the plastic of the tote where it is closest to the light. The suction cups are working great - much to my surprise. Ive been running the light 24/7 for about 10 days now, so not much time over all. I ordered an extra light to have as a back up. If this one dies, I dont want to wait to get another one in the rez.
The new Mega Crop is chunkier than the old stuff. V1 had little hard little balls of something, then most of the rest was fine powder. The new stuff doesnt have the same balls, but does have random sized white chunks of something.
That concerned me at first, because I normally only add a few grams - 5 to 10 maybe - to the rez at a time when Im mixing. Trying to get equal amounts of all the chunky stuff - in the proper ratios - into a small scoop just isnt practical. One time I would get no chunky stuff, and the next time a bunch.
So I took a large scoop - about 60 grams - and dissolved that into about 3/4 of a quart of RO water. It took a two or three minutes of shaking/mixing, but it all dissolved ok. Then I added small amounts of that mix to the rez until the EC was where I wanted it. This worked just fine. Im going to post this in the Mega Crop thread with a pic or two.
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Here is a comparison between some Northern Lights I grew in soil last year and two buds on the C99.
Left most is the NL, center is the one of the best of the C99 buds and right is one of the worst. These are all about 38 days into flower. The NL may have been a tad younger by a day or so.
Maybe this is strain related, or maybe its my PH issues, or its just slow from all the earlier stress with copper, chlorine, brown zombies etc. ??
Here are the full size images.
Soil
Best C99
Worst
Edit: It occurs to me it would probably be a better comparison to another sativa mix. Here is one of my Blue Dream - also in hydro - at about the same age.
One thing I have thought is that I recirculate, which will bring my PH down as the plants excrete H- ions. In combination with the doser keeping things controlled, I have a growing doubt that my numbers are relevant when looking at a run to waste system.
I have started using this PH drop as a cue to do a partial refresh of my tank. I rationalise that it is a sign the plants have eaten a decent amount of the food available and the ratios of nutrients have been moved away from ideal. It is hard to tell but it seems like I am using roughly half the PH adjustment I was using before I started reading this thread.
We shall see what benefits this brings if any when it comes time to cut them down 
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I think everything you said makes good sense, but Im a little curious about this statement:
Is it that you are doing adjustments half as often - and so allowing a larger PH swing before the adjustment kicks in? Or are things running better, so that you only need to do them 1/2 as often?
Or?
The pressure snubber arrived today and I got it installed. Wow! What a difference in noise level from the pressure switch. The tank tops off a little faster than before, which makes sense if the power isnt getting cut on/off at a 60 hz rate at the end. The best part is the noise is waaaay down. The switch now has a nice clean sounding click at the end when the upper pressure is reached with just a hint of buzzing. Im really glad a decided to add this. Im sure the pressure switch will last much longer now and be more reliable in the mean time.
There is still some buzzing though, which means that some of the pressure pulses are still getting to the switch as it reaches the cut off pressure, even with the snubber.
I have no idea how much of an issue this may be when I convert to the arduino pressure switch setup. Im hoping that it will be a simple matter of an offset or doing some sort of averaging of data points. Maybe, once the pressure reaches the set value, wait a few miliseconds and sample again, to see if the pressure dropped back down, and then cut the power if it didnt? Are the pressure readings taken at set intervals or continuously? I guess it will depend on how big the pressure difference is. Might need to do some averaging. I notice that combo pressure/humidity/temp sensor @MicroDoser linked to above has a ‘smoothing’ option. That sounds like what I might need to do. I would think a loop comparing the hi and low pressure spikes would do it?
Mega Crop V2 report. V2 does seem to have more buffer capacity than V1, but it doesnt have the same buffer capacity that the Advanced nutes did. It holds PH fairly well for maybe 8 hours or so, but then it starts back up fairly fast. Once the PH starts going up, it is no faster than the Avanced though, so that is also an improvement over the V1.
The Mega Crop also seem to have less ‘stuff’ visible in the water than the Advanced did. Not 100% sure if thats good or bad. Im assuming visible stuff would be un-dissolved nutes or precipitates, so Im guessing less is better. Its to soon to tell if the plants like it better or not, but it is way easier to deal with during a rez re-fill/top-off than the three bottles of Advanced. Plus the cost is stupid lower.
Yeah, this is what I keep coming back to. There ‘should be’ nothing left in my rez that can drive the PH up, and yet it goes up fast once the buffering capacity is used up.
I have been thinking that it had to be dead or dying algae still in the tote or pipes or pumps. I cant think of any thing else that could be doing it. But - switching to RO, all the chlorine, copper, and now the UV light treatments, should have killed off the vast majority of that crap.
This got me to re-thinking things. I was about to go ahead and buy a new tote and all the related plumbing, but then I decided to test some Mega Crop I mixed up a few weeks ago when we were doing the buffer thread stuff. The sample has been sealed in a mason jar for more than two weeks. It had been reading around 5.6 or so and its now reading 6.1. When I stir it, I can see there has been a small amount of precipitation - which is something @Northern_Loki also noticed when the PH rose in his tests.
Then I remembered that the Mega Crop folks mentioned that their buffer was set to somewhere in the low 6’s - which is consistent with what Im seeing. So, the Mega Crop all by itself, with no action from algae or anything else, tends towards a PH around 6.1.
That makes me think, maybe I dont have an algae problem??
BUT - that does not explain whats going on with the Advanced nutes. Their MES buffer is supposed to be targeted at around 5.6-5.8, but it also wants to go to 6+ after a day or less.
So, if it inst algae driving the Advanced PH to go up, what is?
A new tote and some pipes and fittings will be under $20, so I will probably do that anyway, just to be sure.
Edit: I just mixed up some Advanced nutes in a mason jar and will see how they do sealed up over time. I am expecting them to settle in at a lower PH based on the MES buffer, but we will see…
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I think about it like this.
The periodic refreshing of some nutrient solution means there is less H- ions so I need less PH up to counter that. I have kept the same hysteresis (PH range) and I still allow a swing of up to 0.1PH, it does seem that the doser is dosing less and the PH wanders in that 0.1 PH range more time than it used to.
I have also started doing three days at 5.85-5.95 (for Mg and macro nutrients) then a day at 5.45-5.55 (for zinc and other nutrients) and sometimes a day or two at 5.6-5.7 (just in case).
After a couple of those swings, I drop the PPM from 650 to 400 (which drains about 3/4 of the tank to the level of the pump as the inflow is less than the outflow) then put it back to 650. The largest swing from doing a tank refresh is a 250PPM drop for about 1 hour. PH etc remain within tolerances.
My suspicion is that if your PH swing is infection related then you will see a small benefit that will go away in a day or two. Unless you replace literally everything then there will be a vector of reinfection from the non-replaced kit. I think that even if you do replace literally everything then the air itself is a reinfection vector. It is seeming more likely you are just buffering at low 6’s and your PH will always drift towards that.
I had similar issues with mould one time. What I did was to get an ion generator (UV bulb in bazooka looking thing with a fan, created ozone) which made toxic air and I left it in the room for a couple of days. I reckon a bleach spray would have done as good and would have been a fraction of the price. It did get into soft furnishings without damaging them though.
From reading this thread and the other buffer one, I cannot off the top of my head think of a buffer that works in that range. The simplest answer is that they have the same buffer range as megacrop and are lying about it…
Just a thought, are there nutrients designed for run to waste instead of recirculating systems?
To my thinking they should have different buffers. The recirculating one being higher as it should be compensating for the PH drop from root action on the nutrient solution.
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I don’t recall them noting that they’ve “set” their buffering at a specific PH. The only thing I’ve seen them publicly announce was that their formula is buffered. If you have a reference post on their buffer, please point that out as that will give us a starting point to discuss with them in the future on how they are accomplishing that. Perhaps you mean the PH of MC at a certain EC settles at a certain PH. This is different from the buffer (but the PH does effect the apparent buffer effect). But, even then, I see the initial PH at about 5 when added to RO water (for MC version 1 & high EC).
Naturally, from the formulation, the most obvious buffering component would be a phosphate buffer which has three pKa(s) of 2.1, 7.2, and 12.3. This does not mean the solution will tend to drift towards the pKa. What that means is that the buffering is the strongest near those values. For review, we are talking about the balance between H+ and OH-. If the PH moves, there is something in solution that is affecting the balance. A buffer acts to supply either H+ or OH- slowing the apparent change in the ratio between the two. This does not mean the PH is only at the pKa and it does not mean that the solution will drift towards the buffer pKa. All a buffer does is slow the apparent effect on PH after the addition of H+ or OH- ions (relative to a non-buffered solution). PH will change, just not as great of a change otherwise. The PH may more readily move one way or another non-linearly depending on which side of the pKa(s) the PH of the solution happens to be at.
The greater the concentration of the buffer, the more ability the buffer has to slow the change in the ratio. If anything in solution is reacting with the buffer, the buffer will eventually deplete on one side or the other of the pKa value. At some point there is no longer any buffering action. The further away from the pKa, the weaker the buffer (less capacity). This is the reason you want a buffer with a pKa value near your target PH.
If you take a buffer with a pKa value of 7.2 and adjust the PH down to 5.8, you are more than 1PH away from the pKa. This buffering at the 5.8 will be weak. You are more than a 1PH away from the pKa. Now if you were to slowly increase the PH back towards the 7.2, you would see the buffering action increase slowing the change of the PH. It would reach the maximum buffering effect at 7.2. As you exceed this value you’d again see the buffering action slowly decrease.
Note: In reality, a complex mixture of chemistry will probably have a variety of buffering effects at a variety of pKa values as the ions form a variety of different complexes with the H+ and OH- ions and the available salts (Na, K, etc). Sometime that might produce an insoluable precipitant (bad) or a soluble precipitant (maybe ok).
MES may be a sensible guess but MES is expensive and, if they are using MES, it is also likely that the concentration is low. Could be a combination of buffers, MES + citrate + phosphate. Don’t know since AN likes to call things “proprietary”.
The greater the concentration of a buffer the greater the capacity it has to buffer against a change in the quantity of H+ or OH- ions. It becomes “stronger”. It has more “capacity”.
However, you can’t just up the concentration without being thoughtful. For instance, a phosphate buffer is also a nutrient source. If you were to increase the concentration of a phosphate buffer, you’d also be altering the nutrient ratios. Obviously, at some point, it could have adverse effects.
For nutrient formulations, the addition of monopotassium phosphate will give you a buffer. It will be weak at the target PH because it is greater than 1PH from the pKa and the concentration is limited for plant health. The buffering provided, in essence, is a bonus that is gained by using this particular chemistry as opposed to something else.
If the quantity of buffer available in solution is low, the “capacity” of the buffering effect will likewise be low.
Take a critical look at the curves in the buffering experiment thread. Notice how the MC(v1) is buffering. (perhaps, I’ll titrate some AN to compare. Let me know what you are using). Then, take a look at some of the other curves and note how they change as the concentration of the buffer is increase. Particularly, note how the location of the pKa values of the buffer becomes more obvious as the concentrations increase.
The best choice of a buffer for a particular situation has the following features:
- pKa near your target PH
- allows high concentration before phytotoxicity
- does not sequester/cause precipitation of desired nutrients.
- Any chelation of salts is synergistic (e.g. keeps nutrients plant available)
To start, there are only a few standard buffers that will meet (1). MES appears to be the most promising at the moment. Just so happens the pKa is ~6.15 (temperature dependent). +/- 1PH provides buffering in the region ~5.15 - 7.15 with a suggested PH buffering range of 5.5-6.7 for a strong buffering effect.
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I see how you are doing it now. That sounds like a good system you have set up.
I cant remember if I asked this before - how much PH down do you think you add between rez changes?
Im asking because one of the reasons I have been wanting to find a better buffer was to reduce the amount of PH down Im using. As @Northern_Loki has pointed out, adding more phosphoric acid can mess with the phosphorous feed ratios.
Thats one reason I originally switched over to Sulfuric acid. From what I have read, the plants can tolerate excess sulfur pretty well - so the extra sulfuric acid doesnt unbalance the nutes.
But - if you are doing fine adding a lot of phosphoric acid, then maybe thats not as much a worry as I thought.
Yeah, thats the real question - is this PH rise just the nature of the beast with my nutes/water combination OR is it zombie algae related - OR - some of both.
So far, nothing I have done has really made a significant dent in the situation - which tells me I havent gotten to the bottom yet as far as WHY.
The RO water helped a good bit, the chlorine and then the UV helped some, changing to Advanced Nutes helped a lot, but only for a day or so, then its back to normal.
Arguments in favor of infection with algae or some other bacteria, is that adding chlorine did make a difference, and keeping the UV light on is continuing to make a difference. As you said above, there is certainly still some crud in the system that would be a re-infection vector.
The main argument on the other side - that its NOT infection related - is that the Mega Crop, and now the Advanced also, just seems to want to go to 6+ PH even if left in a sealed mason jar.
I started a sample of Advanced Nutes in a mason jar late yesterday. It mixed up at 5.7 PH. Tonight its at 5.9 PH. Thats about the same PH rise I see in the rez over that same time period. The only difference is I add calmag initially in the rez, which makes the starting PH closer to 5.5. After the first 24 hours the rez is usually up to 5.7, so the same .2 rise in PH in a sealed jar as in the rez. Thats after just one day. It looks to me like the Advanced is going to do the same thing the Mega Crop is doing - go up into the low 6’s all by itself in a completely sealed system.
So, I have ‘evidence’ that seems to be pointing to infection, and other ‘evidence’ that the nutes just do things this way no matter what.
Im going to go ahead and replace the tote and all the plumbing up to the pressure pumps. Thats as far as I can go in a short time. I dont want to leave the roots to dry out. The tank holds enough to run the misters as long as 36 hours or so, but I cant easily replace anything after the pumps without re-doing the plumbing significantly. That will have to wait. That should tell me if there is something in the rez and those pipes causing or contributing to the PH rise. It may only last a day or so, but it will be a good data point.
The Advanced feed chart doesnt distinguish between drain to waste or recirculating - just the one chart. I would assume it assumes recirculating as thats what the majority of folks do.
I got that from an email they sent, but in looking back on it, they were not really clear. Here is what they said when I emailed about buffering.
This is what I got:
New MC formula released last month has improvements in bufferings. Also, the range for Mega Crop is 5.5 - 6.5 pH.
I am sure I found an MSDS somewhere that listed MES as one of their ingredients - but now I cant find it again, so maybe Im mis-remembering? I figured that was the reason they were so $$ was the MES.
The stuff you post on buffering it starting to make more and more sense to me. I think its finally starting to sink in somewhat, because I was able to follow almost all of that fairly easily this time around.
Yeah, so far MES looks like the ticket to me too - but the $$$$ is a killer. Plus - which variation of MES should be used? I have found at least three different ones listed in the buffer calculators on-line. Plain MES (I think the acid form?), MES Sodium Salts, and MES Potassium Salts.
It looks like the plain MES can be used alone or with one of the others? Thats not clear to me yet.
The target PH of the buffer can be adjusted as @Northern_Loki said above. I found a few websites with buffer calculators that allow you to pick which buffers you want to use, then calculate what amounts of the two (strong base/weak acid, etc) to mix together to get your target PH.
https://www.aatbio.com/resources/buffer-preparations-and-recipes/
and here is the one for MES
https://www.aatbio.com/resources/buffer-preparations-and-recipes/mes-ph-6
There is another one from Sigma Aldrich, but I have not played with it. It lists three different MES buffers, plus a host of others.
BUT - none of these tell you how much is tooooo much for the plants, so Im not sure how useful they will be other than as a guideline for mixing ratios.
Thats a pretty expensive test to do - but Im using the Advanced Nutes PH Perfect Micro, Grow, and Bloom three pack. Three quarts runs around $35
I think I need to pin down what the source of the problem is better - before spending more money on possible solutions.
So far, it looks to me like the natural tendency of both Mega Crop and Advanced nutes (when mixed with my RO water at low EC values - below 1.2mS) is to start around 5.6-5.7 and then rise up to the low 6 PH range within a few hours.
Is that just the way both of them work - or - is my RO water a factor as well. From what I have read, RO does not always remove all the carbonates in the water, so that could be a factor as well. I dont see any way to address that problem though other than buying hundreds of gallons of distilled water for every grow - which is a non-starter.
Add to that that I also seem to have algae crap in the air and water which will re-infect the system on an ongoing basis.
I am hoping that - if - I can clean the system well enough, that the UV light will prevent re-infection long enough to get through a grow cycle. But - thats still gong to leave me with the natural PH rise that either nutes do on their own.
Using MES as a buffer is just going to add too much cost to my grows, so Im stuck using either phosphoric or sulfuric acid. I cant tell if there is any significant difference in how long the PH holds between the two acids. The phosphoric may be a tiny bit better, but that may just be my imagination because the mix I have is stronger than the sulfuric. The sulfuric should be safer as far as phosphorous toxicity goes, but maybe thats not really that much of an issue.
Speaking of MES costs - the question is what molarity is needed to do what I want?
Those calculators start with a molarity of 0.5 for the MES. That works out to just under 4 kg of MES for 40 liters of solution = one rez volume for me.
Over an 8 week grow, Im going to use roughly 300 liters total. Thats roughly 25 killograms of MES. A quick search on ebay says that will cost $2100. Thats just a tad $$ for me 
But - do I NEED 0.5 molarity or can I get by with a lot less? Or, would the salt versions do better?
I can get 100 grams for $20 from that same guy, so I may try that just to see how much it takes to slow this stuff down. 100 grams would have a molarity of .0134. Thats going to get very $$ if I have t do that every few days.
My brain needs replacing. I totally forgot about Ion Exchange resins. I never did email DOW to find a replacement. Im going to do that now.
Even if they are $$ up front, if they can be re-used up to 100k times, that would make sense over time.
I figure I only need 20-30 grams. Maybe we could do a group buy if anyone else is interested in trying some out.
I will keep you all posted…
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I have a 5l bucket with about 300ml of KOH in it. This lasts well over 6 months. After the first three months I top it off with some more water so I can dose more accurately, 300ml/5l is still a bit strong, to be honest. I used to add far more PH down when I ran with tap water, then the tendency was to always drift upwards, now I run RO the small amount of H- ions shifts that to a mainly downward trend after a day or two so I use dramatically less PH down. It has made about 0.2GPW difference to the system overall.
OK, to be sure whether it is an infection or not you need to have some water, nutrients, and a sealable container you know has no infection in it. I would say to get a glass jar, like a kilner jar, that you can sterilise with tablets or put in the oven (or both). Sterilise some water, either by boiling it or using some sort of tablet (boiling probably better). Dose and PH adjust the water, fill to nearly the top to eliminate the CO2 effect from the air, seal and observe. If a sealed container does not change PH then you know it is something external to the solution. If it changes, you know it is something in the nutes and PH adjuster (or the ratio of those items).
If you find the effect is external then you could half fill the jar and shake it regularly to see if it is CO2 or infection. If it’s the nutes, it’s the nutes…
As controls you could have plain water, PH adjusted water, and water not PH adjusted with nutes in.
By eliminating the effects from various areas, then observing the results, it should allow you to eliminate false causes for the PH drift and isolate the actual cause ( or causes ).
If you already have the jars, it would be free.
EDIT :
Yeah, if solutions to your problems are getting to those prices, it is cheaper to buy or build a doser and then you can go on holiday for a fornight and still monitor and care for your plants…
I still have the opinion that is where all this is going.
I think of a growing system like a drag car. Some people just take their daily drive to the track and see what it does. This is like growing in garden centre compost grow bags. Sure you will get a time (yield/result) but everyone around you will get a better time.
So you adapt your car, you add a turbo, better exhaust etc. In the grow world you may get LED lights, a better fan, change to hydro etc.
Eventually, you have a 2500HP funny car doing 5 second 1/4 miles. Or you are designing your own HPA system…
To my mind, advanced systems like the one you are designing are like top fuel drag cars. Every part needs to work in harmony with all the others just so the whole damn thing does not explode in your face half way through the run. You are monitoring your PH much mroe than a lot of people and you see why this is also required for your system. It is so highly tuned that small differences in PH make large differences in performance.
Without a doser, you are facing a LOT of monitoring, dosing, and fiddling to get things to stay within tolerances.
The electronic side is fairly easy, as is the code, but like growing it is an endless subject. Just like growing it is best to just start rather than research too much.
Glad my experimental results are matching those done by people with far more resources than me.
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Im going to post some links and quotes here for future refference - so I dont forget
This one has some safe levels for MES and other interesting info.
Abstract
2-[N-morpholino]ethanesulfonic acid (MES) buffer or Amberlite DP-1 (cation-exchange resin beads) were used to stabilize substrate pH of passive-wicking, solid-matrix hydroponic systems in which small canopies of Brassica napus L. (CrGC 5-2, genome : ACaacc) were grown to maturity. Two concentrations of MES (5 or 10 mM) were included in Hoagland 1 nutrient solution. Alternatively, resin beads were incorporated into the 2 vermiculite : 1 perlite (v/v) growth medium at 6% or 12% of total substrate volume. Both strategies stabilized pH without toxic side effects on plants. Average seed yield rates for all four pH stabilization treatments (13.3 to 16.9 g m-2 day-1) were about double that of the control (8.2 g m-2 day-1), for which there was no attempt to buffer substrate pH. Both the highest canopy seed yield rate (16.9 g m-2 day-1) and the highest shoot harvest index (19.5%) occurred with the 6% resin bead treatment, even though the 10 mM MES and 12% bead treatments maintained pH within the narrowest limits. The pH stabilization methods tested did not significantly affect seed oil and protein contents.
Another one with interesting notes on MES and resins.
https://dl.sciencesocieties.org/publications/aj/abstracts/80/2/AJ0800020213?access=0&view=pdf
Abstract
Plants grown in hydroponic culture make useful experimental models for soil-grown plants. However, a major problem of nutrient solution culture is the adequate buffering of solution pH. Four methods of controlling pH in hydroponic culture of winter wheat (Triticum uestivum L. ‘Centurk’) were compared at two levels of Ca (0.2 and 2.0 mM) to determine the buffering method with the least effect on the uptake of essential nutrient elements. These methods were: (i) manual titration with NaOH, (ii) Amberlite DP-1 weakly acidic cation exchange resin loaded with Ca, Mg, K, and H, (iii) the organic buffer, 2-(N-morpholino)ethanesulfonic acid (MES), at 1mM; and (iv) MES a t 5 mM. Five-millimolar MES gave the most consistent control of solution pH. However, it also inhibited Zn accumulation by wheat. One-millimolar MES did not maintain the solution pH as well as 5 mM MES, but it did not significantly alter the uptake of any essential nutrient element. It is recommended as a pH buffer for the hydroponic culture of winter wheat. Resin in membrane bags did not adequately buffer the solution pH. It also removed some Mn and Zn from solution, thus depressing their uptake by wheat. Resin in a pump system adequately buffered the solution pH until its effectiveness was limited by the flow rate through the resin bed. Adequate buffering of solution pH was found to be critical for experiments that study the interactions between Ca and other nutrient elements. With the pH buffer, MES, the previously reported effects of Ca on depressing Mg, Mn, and Zn accumulation were observed. However, in the poorly buffered treatments, these elements tended to increase slightly with increasing Ca levels, perhaps due to the effect of Ca on maintaining root membrane integrity in an acidic environment.
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Sounds like they had nutrient deficiences if they restricted their PH to a value too strongly. This makes sense, I am settling on 80% of the time at 5.9, 20% at 5.4-5.6. I get an Mg def if I stay at 5.9, and pale plants if I stay at 5.4-5.6.
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I’m interested in these for sure. Keep us posted what you hear.
In the meantime I’m re-reading all of this info from you guys on buffering. Going to take a bit of brainpower to make sense of all of this data. Good research guys and super informative.
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