Don’t know what the “i” is but here is another source:
I can not recall but I believe for iron you’ll need to look at the PH compatibility for the different chelates.
Nevermind,
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Thanks! It never occurred to me to check PH issues. Looks like it wont be a problem after all though.
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Will be interresting to see, how you like running sterile aeroponics.
Might work really fine, as your not recycling your water as I recall.
I stoped using my UV filter, unless I ran into issues.
Then they can be a great help, to save your crop.
But didn’t like the sterile growing, as some of the strains I ran, suddenly didn’t like the feeding plan.
That prev had cropped in at 1.2 gpw, then dropped below acceptable.
And bounced back up, after I went back to culture water.
Adjusting the feed plan, would surely made a difference.
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LOL I’ve been TRYING to run sterile, but these f@#%ers just wont die! You kill them a hundred times and they just get back up and keep coming! I feel like Im acting in a zombie algae apocalypses war! 
Thats encouraging that the UV worked to save your crops. Did you see signs of iron deficiency? The change in how they liked your feed makes me wonder if iron was being precipitated out by the UV.
Did you use just a bare bulb like Im doing or a pro unit?
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Time for some pics.
Here is a GIF of the last 9 days that shows the stretch.
Front view with lights off. This is a few days ago.
They are starting to frost up nicely and to smell. Its not a bad smell at all. The stickyness is making trimming a messy job. Time to break out the nitrile gloves.
No new root pics. No big changes there other than more filling of the chamber. I may need to do some trimming of the umbrella portion before much longer.
The mat on the bottom is slowly showing more white, but the progress seems a little slower than it did for the upper section.
I will try to get some good pics tomorrow. Its interesting to me to see how the hairs vary from one section to another. Its pretty easy to tell when the mist is ‘good’, or ok, or not so good just by the length, color and quantity of the hairs.
Of course, the brown sections just look brown and bad in comparison. I am more and more convinced that once the roots turn brown, they dont turn back into fuzzy roots. You have to wait for new fuzzies to grow out and cover those areas and that takes more time.
Its about 20 days into flower.
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I ran a external UV filter, you hooked onto a small pump, circulating water thru the unit.
Somthing like that, they are rated for X galon, I had a 1000 Gal unit from a Koi shop.
It took care of the root rot, not like magic or anything but the rot stoped spreading as fast.
We where able to finish the grow, and pull some weed and not go bankrupt.
It worked well with H2o2 treatment, and then run the UV filter as well.
Im not sure what it was, that changed by the UV filter. Honestly I think it was the beneficial bacterias and culture water, that helped the plants to uptain what they need. Even tho the nute mix wasn’t all perfect, but it’s impossible to say and more then 10 years ago.
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That’s the name of my new punk band who do songs about fermentation and world ending man made disasters.
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Looking good. No signs of nute def, growth seems strong. Looks to be filling both the upper and lower chambers well.
As an aside, I recently noticed that my ‘PH up bucket’ has run out of PH up and after reading these threads (PH, HPA, etc) and commenting, I have decided to not drive there and refill it, but instead to change the software remotely and tell the machine to pump out some nutrient solution if the PH drops too low. The pumping out of some solution and the float valve addition of some RO water (automatically adjusted by a doser on the fly) is doing a good job of keeping the PH up.
I am thinking this is a better way of keeping the PH up because now I will have more food overall in the solution, and less PH adjuster. The H- ions put out by the roots are doing a good job of keeping the PH on a downward trend. I now run a waterfall aeration, very thin film NFT, recirculating/run to waste hybrid system controlled by a computer, hehe.
I have noticed the RH% has jumped by 5-10% (day and night readings) since doing this which I read as the plants being more bioactive in their environment and that is always a good thing.
As I only see my plants at most every two weeks, I have had to gain skills in determining their health through secondary sensor readings…
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Finally had a chance to reread this and digest the info… 
That makes me feel a bit better. This is the best part of having more than one person going down the same path – you thought of things I hadn’t and realized there really is no issue. I ran into the discussion about the tank, did a small bit of research and dropped the idea because I wasn’t 100% sure.
I really did like the idea of a UV sterilizer and like you said, $15 is hard to pass up. I went ahead and tossed one in my Amazon cart, so we’ll see if it makes it into the system or not.
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If you wanted a bit more volume being sterilised at a time, you could use 4" (100mm) SS air ducting. AFAIK end caps etc are available so you could make up something fairly professional looking for not much more outlay.
Would be pretty easy to fit water/air/light tight fittings to the end caps.
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I’m not sure it’s really about wanting more volume at a time. I have up to 75 gallons of water in my res and a pump circulating between 1-25GPM, so the super low-flow systems might not work for me. (Though if the water is passing through multiple times an hour, does that really matter?)
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In our situation, I dont think it matters that much.
It takes a certain amount of ‘exposure’ to the UV light to kill one of these zombie bugs. You can increase the exposure three basic ways.
-
more power. More watts will kill faster at longer distances. Think lazer blaster vrs sun lamp.
-
More exposure time.
You can increase exposure time by pumping the water by the lamp at a slower pace = lower volume/hour - or - run the same water by the lamp more than once.
- add more UV units in parallel or series. Both will increase exposure.
Im going with #2. My circulating pump in the rez is 390 GPH. Im going to set up the lamp so that it is in a relatively calm part of the rez - probably in the center, out of the direct blast from the pump. That will mean slower moving water right at the lamp for longer exposure. The water will cycle by the lamp multiple times each time the pump turns on. Right now Im running that pump one minute every 5 minutes, but I may extend that to something like 2 to 3 minutes ON every 10-15 minutes. Maybe.
I dont think we need the lamp on full time, plus I dont want to precipitate too much iron. That will also extend bulb life by not running full time.
If I add a stainless tube to protect the plastic, I will do the same - just direct a small portion of the total pump output through the tube.
Interesting idea! I may even have some SS ducting laying around…
Exactly! I love these forums for that exact reason. Most of my best ideas come from other people 
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That sounds like an amazing system you have set up. Its interesting to me that you have the exact reverse of my problem as far as PH drift.
How much of your nute solution goes to waste and how much re-circulates and how do you decide on a ratio?
The local hardware suppliers in my area dont carry any reasonably priced SS ducting. The stuff I have is aluminum, which is less than ideal.
I did find that ABS pipe contains carbon black as a UV stabilizer. Here is one note on that.
7.0
WEATHERING OF ACRYLONITR
ILE-BUTADIENE-STYRENE (ABS)
ABS pipe usually contains carbon black to provi
de protection from sunlight. The effects of
ultraviolet radiation are subs
tantially reduced in pipe so protected and permit the use of ABS
pipe in outdoor applications. The largest outdoor
use is probably plumbing vent pipes of
drain, waste and vent (DWV) systems that are
fully exposed to all climatic conditions.
Prolonged exposure of such plumbing vents has
not affected their performance. Close
examination has shown that only a very thin su
rface layer of the pipe has been affected by
sunlight, even after several years’ exposure.
Sounds to be like ABS will work fine for what we want to do - and is dirt cheap because I have a bunch of scrap pieces laying around
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My doser takes care of that.
I have a desired PH range and if it is too low I activate the irrigation pump for ~20 seconds. A rough calculation says that is about 8l of a 100l tank. Raises PH about 0.05-0.1 (if it raises more than that it auto adjusts the pump time) Might happen two or three times a day?
Works out to be a tank change every four days ish. Buckets hold enough nutes for 20 days easily. If this continues with no problems (and does not cost too much in food) I may keep this up because it means I will be using just a few tablespoons of PH down at the start, then no PH adjustment at all for the rest of the cycle. I like that idea.
My PH downward drift is due to the acidification of the nute solution as a result of the roots eating. Recirculating allows this to build up and overtake the other effects. Before the plants get large enough, I also suffer rising PH.
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Interesting again. I dont think I ever had the PH falling in my last hydro grow. The only times I used any of my PH Up was running soil when I over dosed with PH Down. Im guessing that in my case, the upward trend caused by my water, and algae issues over whelmed the root caused downward drift.
I am in awe of your setup and the automation you have done. Jealous too
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I asked the Mega Crop folks about their iron additive, and its an amino acid, so not one of the EDDHA UV resistant types, but they said not to add anything unless an actual iron deficiency showed up - which was my plan anyway.
Just got an email back from Advanced Nutes:
In the pH perfect Micro (with the gorilla on the bottle)
We use:
Iron DPTA, iron EDDHA, iron EDTA and an Iron Amino chelate
So you should be in good shape with most standard UV filtration methods
I drained the dregs in the rez two days ago and partially filled it with fresh AN nutes and pre-shocked RO water at around 4-6PPM chlorine.
It stayed nice and clear and was holding PH at 5.7 until earlier this afternoon- maybe 36-40 hours or so. It was clear in the AM, but cloudy by 5 PM. PH was still ok at 5.8. Its now 2AM and even more cloudy plus the surface scum is back and PH is up to 6.0
So it looks like the chlorine only keeps the zombie shit down for a while.
The UV light should be here tomorrow. Im really hoping it will keep the stuff from rising from the dead. Im not wild about using this much shock. Its bad for my little hairs
Neither did I until I went RO. Using normal tap water the drift was always strongly up and I only ever needed PH down. Removing the hardness from the water reversed that, but only once the roots put out enough H- ions. Before that point, the drift is still up.
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File this under not really useful information, but interesting anyway…
Fuzzy hairs act like Velcro when two shoots touch each other. Ive noticed that when Im messing around in the root chamber - taking pics or adjusting nozzles - that if I touch or bump into the root ball, the roots will stick together very strongly. Dents and dings in the root mass dont just pop out either. They stay there until the dent gets over grown by new shoots. Ive tried teasing two that are stuck together back apart, and it just doesnt work unless you tug really hard. Putting that much pressure on the fuzzy hairs just crushes them or rips them off.
That angled dent in the bottom center is where I dropped my cell phone trying to take this picture. That dent will still be there until it grows over. You can still see a trough going from the net pot down where I pressed my arm against the root ball a few weeks ago.
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