Oh good to hear that they dont destroy you. Mine happen very infrequently, but when they do, feel worse than being shot or stabbed. Maybe closer to being shot first, and then stabbed into the bullet hole with a pair of linesman pliers. 
Yes it was my hydro guy indeed saying that algae is our nemesis here. 90+% of his business is coco or promix
Another âinterestingâ new result. Fortunately, this one looks good instead of bad.
I am not sure this is a direct cause/effect, but I added some chlorine/pool shock to the rez about 36 hours ago and adjusted the PH down from 6.2 to 5.5. I just checked the rez and its still holding at 5.7!! Plus, the water drawn from the accumulator is down to 5.9 from 6.0 the last time I checked.
On the down side, the water in the rez is still scummy. A brown film instantly forms on anything I stick in the water - like my PH meter. It may be a little less, but its still bad. The water might be a tiny bit less cloudy, or maybe not. Thats hard to judge because it is still somewhat cloudy.
So, maybe this wont be such a big problem after all. I wonder of using the RO has lowered the concentration of brown crap enough to let the chlorine knock it back or keep it in check - at least the PH raising part. Im not happy with the scum at all though. That means clogged filters, so Im going to need to keep up with that.
Maybe.
Maybe you have already done enough so that a new cutting, not already infected, would do better. gain/effort=whether it is worth it. Would more work get you enough of a gain to make it worth the effort?
It is entirely possible.
I very much suspect that a fresh cutting when it is time would do better than the current one (which seems to be doing great). In solutions with less âstuffâ in, acids and alkalines have a greater effect, and so the pool shock might be more effective. It might be more effective if it was the very first thing added to pure RO water than if it was added later.
Good enough, is good enough after all. But only you can decide what is good enough 
At this point, I dont think extraordinary efforts are going to pay off enough to be worth it. I wont know for sure until I harvest, but I think Im going to have a good haul this time around despite all the PH/rez issues. Its hard to justify big expenses if your not increasing yield significantly. Im sure my yield per plant will be way up from earlier grows. I think my gms/watt and gms/sq meter/day should still be decent as well, but maybe not my best. I know I lost a good two weeks on this grow from the copper treatments. It will be interesting to see if HPA can compensate for that.
On the other hand, I often do silly things, and/or go to a lot of extra trouble just because I feel like it, or get obsessed with some technical detail, rather than because its really a good idea - like trying to grow fuzzy roots!
I think thats true. If I can avoid major stress on the next grow, I feel confident that it will go much better.
My problem with âgood enoughâ is that I tend to focus on or get hung up on details and I am easily sidetracked by technical challenges. That makes it easy to loose track of the over all goal sometimes.
I think I have a bad mix of OCD/obsessive/compulsive, and just plane old lazy. Those two sides to my personality are constantly at war! 
Iâll have to see how things go this next run. The last plants seemed to have plenty of extra space around the roots and the haul was still good, but enough has changed in this iteration of the system that anything is possible. 
If the growth rate is fast enough I can always switch over to going straight into flower from the cloner and just add more plants per basin. (Iâm setup so 4 per keeps me legal.) That would reduce my yield but would keep roots under control and should be made up in the time to harvest. Still lots of playing to do before I finalize how Iâll scale this.
First time I dealt with them I had to call EMS to take me to the ER. Was a horrible experience that lasted the entire week of Hurricane Katrina. (I watched the news 24/7 while I was in the hospital.) I donât wish that nightmare on anyone, ugh. Luckily I havenât had a recurrence. Best of luck man!
This must be a common set of traits in us HPA weirdos. 
We are all rooting for you (get it, haha) and learn a lot from your experiences. The details are where the gold is sometimes.
FWIW, Iâve had a test solution sitting out for good amount of time at PH7.4 or so. This solution has some citric acid as a buffer and I havenât seen the same amount of that tan precipitant (that seems to accumulate over time) as Iâve seen in the past.
The other interesting effect with the citric acid is that it moved the re-soluable preciptants way up on the PH curve during the titrations. Donât know why, could be the chelating action of the citrate complex or a maybe a change in the ionic strength of the solution. Interesting.
I almost missed this - sounds like a very good idea to me. I have been pre-drawing RO water and storing it in a 5 gal bucket to reduce the time for a rez top off. It occurs to me that gives that water more time to get contaminated. I think I will start adding shock immediately from here on out. I will also start keeping lids on the stored RO water. If I start doing the short re-fills - not filling the rez all the way - I will stop pre-drawing the water. Those things should all help reduce the amount of contamination at the start.
Thanks for that idea!
It occurs to me that I have never had even close to this volume of roots on my previous grows - even with 4 plants, and I still had nice yields. On my last hydro grow, I bet I had less than 10 gallons total between three plants. Probably closer to 8 gallons. Even on my soil grow with 4ea 5 gallon pots, Im guessing the actual root volume was not much more than 10 gallons.
Im not at all sure you need huge roots or how much it helps the grow. Heck, huge roots may even take away from growth of the canopy.
So just ignore me
LOL!
Very interesting points. I wish I was better at chemistry. Ive been struggling with my homework on this whole buffering subject. Im still not really âgetting itâ. I keep telling myself that staying heavily stoned the last several weeks has something to do with it.
Your results have had me second guessing my choice of PH down. Im using sulfuric acid - a strong acid - rather than the more traditional Phosphoric acid - which is a weak acid. I wonder if that choice has had any effect on my buffering issues?
I guess I will need to get some phosphoric acid and try it to know for sure.
No way, itâs these strange observations that is making the HPA grows so much fun.
Ah, this sounds like a very likely infection vector. Something with a lid would help. Airtight would be even better.
RO water is especially supportive of bacteria etc. Having no chlorine (or anything really) to kill it off, it grows without restriction. When you use it for drinking water, an RO unit will often come with a UV purifier to kill off any bacteria that are growing in the expansion tank.
Good points. Ive been putting a lid on, but have not been super serious about keeping it sealed.
Just topped off the rez and added shock to the RO as it was being drawn from the filter. Im going to do that from now on as well as keep things covered/sealed much better.
This stuff is in the air though, and I cant keep air out of the rez, so Im more focused on killing it once it gets in.
Interesting you mentioned UV units. I was just thinking about the possibility of adding a UV unit to the rez that would run the whole time - much like in a fish tank. I like that idea better than using shock, which can damage my little fuzzy hairs
I cant think of any real downside to doing that.
I havent looked at UV sterilizers in a decade or three, so I need to do some reading on that. No clue how $$ they are these days.
Edit: wow! UV sterilizers have come way down in price - like more than an order of magnitude since I last looked! I am going to try this for sure.
I ordered one of these.
https://www.amazon.com/gp/product/B07L8YJ4PP/ref=ppx_yo_dt_b_asin_title_o00__o00_s00?ie=UTF8&psc=1
No reviews, but it looks just like several others with reviews - all of which are mixed. Its main feature is low cost = $15.
I looked at a bunch of more expensive models, but they all have issues, and bulb life os one of them. Replacement bulbs for many of them are $$, so this seems like the best bang for the buck.
I was going to stick it in a PVC pipe and run my pump through that, but I realized I dont have fish in my tank, so no need to shield the bulb.
Im going to set it up on the same timer as my circulating pump so its on when the pump is on.
If this works, Im going to be super happy.
That is new to me as well. Looks like it would clean a fair sized tank, with circulation. Means I could run a degree or two warmer during veg to et a bit more root growth.
I think I will look for one on the UK Amazon and connect it to the same circuit as my lights, in case of light leaks at night.
And that price! (bet it isnât as cheap here)
There are several similar items/prices on Ebay as well.
Ive been doing some more reading on UV sterilization in hydro. It looks like the only down side is it can cause precipitation of some micro elements in some of the nutes. I need to do more looking but it seems like some types of chellated iron are most susceptible to the damage. This can cause iron deficiency. Another site mentioned manganese and one other micro nute as things to watch out for.
It also sounds like full time use isnt needed once the main infection is knocked back. I think Im going to put mine on a separate timer and maybe only run it a few minutes out of every hour. I will be reducing the load a lot just by using âfreshâ RO water, so the UV will only have to deal with new infections from the air.
I think it will help me a lot that Im not re-circulating.
Having the bulb exposed should kill off any lingering algae/slime build up on the walls of the rez that has started since my last cleaning. It wont kill off anything that isnt free floating in the water though - like the inside of pipes, pumps etc and the rest of my system. Hopefully, all the stuff tht has built up on surfaces will get killed by the chlorine and will NOT be able to re-grow.
This might take some time to happen, but I think this could solve my issues without having to replace all the bits and pieces.
Its been several hours since I changed the rez for fresh AN nutes and pre-shocked RO water, and so far, there is no sign of cloudiness or scum on the surface. Im hoping this holds up over time.
Itâs funny how often our ideas match up.
I had thought of this a few weeks ago and went down the rabbit hole. I found a few folks talking about problems with bennies, but since weâre both running sterile resâs I didnât worry much. I was hoping to do UV in the flowing part of my system so I didnât have to add another loop but the higher GPM units are quite expensive. That led me down the path to just buying the lamp â thinking I could install this directly into the res.
The one thing I found there is that while my res is UV resistant extended exposure to high UV will degrade the material. When I kept reading I found that is why the big units are more expensive â they actually store the bulb in a stainless tube and the bulb is covered by a quartz shield to protect it. These submersible bulbs work in fish tanks because they are glass, but PVC is not recommended for extended direct sunlight applications, so I imagine a UV bulb would cause all sorts of havoc when directly inside a PVC pipe. Just something to keep in mind.
I really like the setup theyâve built for the Zipfarm, shown here.
The problem is each of those UV clarifiers are $500 and they use two for the higher volume flow. I havenât ruled this out yet and I even have a location set aside to add the UV later on if I feel the need, but I think this time around Iâm going to start without one. (Even though the geek in me just screams ORDER IT!)
I worried about that too, but decided it wasnt that big a deal for a couple of reasons.
The inverse square law is on our side. In all those cheaper - plastic - sterilizers that have a housing surrounding the bulb, the bulb is very close - often touching any plastic parts. However, with just the bulb by itself, it will be easy to suspend it in the tank so its much further from any plastic. I should be able to more than quadruple the distance to any plastic, so 1/16th the exposure or less.
If it did prove to be a problem in my case, a new tote is usually $10 or less on sale. I think I will be able to feel and degradation long before the tote fails.
If the plastic does start to wear, the solution would be easy - just stick the light in a short piece of stainless pipe and direct the pump outflow to force water through it. A short piece of 2" SS pipe should not be too $$ at a metal recycling yard.
Im pretty sure you can also get UV stable plastic pipe. ABS should work fine as its used outdoors as vent pipe exposed on roofs. Im also thinking I read that some forms of plastic electrical conduit - the grey stuff - are UV resistant, but need to check on that. It might be cheaper to buy 16" of scrap SS than a 10â length of pipe from HomeDepot though - and more certain of safe use.
As far as flow rates needed to kill stuff, in a hi flow system - like those zip farms - you will need lots of power or use more UV units. The UV doesnt have time to kill stuff if the water flows through too fast, but if you slow it down, it works fine. The other thing is re-circulating inside the rez will run the same water by the bulb repeatedly to give more cumulative kill power.
I think in our situation a smaller, lower power UV unit would work fine as long as the water can circulate through enough.
I noticed he mentioned needing to add extra iron to make up for the precipitation due to UV. Guess I better look up what specific product I might need to get to supplement any iron losses.
I also need to go back and see which specific chelates of iron worked well and which precipitated the most - then see whats in these AN nutes, Mega Crop, etc. I might be fine or I might need to add something.
Im jazzed about the potential for this, in combination with RO, to stop the algae.
Almost forgot about the bennies you mentioned - if this UV kills the algae without needing any chlorine, or copper, then it will enable the use of bennies if you spray them directly on the roots. You still wont be able to put them in the rez, but thats not a concern for me. In fact, I dont want them in the rez. Even the good bacteria are slimy
Found the notes on iron chelates and UV.
From that article:
Note that the fact that free Fe is generated does not mean that the Fe is precipitated but merely that the chelate has been destroyed, which is the first step before the Fe can precipitate. From this it is clear that different chelates have very different stabilities and in this case chelate i-Fe-EDDHA had the largest stability while other chelates had much poorer stability against UV radiation.
Now I need to find some âi-Fe-EDDHAâ stuffâŚ
I think I will email Advanced Nutrients, and Mega Crop and see what they say about UV and their nutes and if they will say what iron type they use.
Turns out its easy to find. This is the first one I found so Im sure there are cheaper options.