That’s it right there.
Citric doesn’t hold pH like mineral acids (phosphoric, sulfuric, etc.).
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This was happening when I was using general hydroponics ph down as well… hmm… have a suggested ph down?
Thanks
The GH PH Down is fine. Its phosphoric acid. You can buy concentrated phosphoric acid for a lot less than the GH product though. Check Amazon or ebay or you may be able to find it locally.
The least expensive option is sulfuric acid from an auto parts store. I dilute mine 1 cup to one gallon of water. Just be sure to always always always always always add the acid to water. Add it in slowly - and - never never never never add the water to the acid. The mixing order is important or you could get the acid splattered all over the place - including you. Wear gloves and goggles.
Sulfuric acid is used by pretty much every large scale/commercial hydro grow around the world. Partly because it works and partly because its cheap.
I agree - citric doesnt work all that well. Plus its organic, so bad in hydro.
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General Hydroponics pH down is a blend of phosphoric acid, citric acid, and MAP.
I use Cyco pH down because every hydro store carries it, it’s solely phosphoric acid, and it’s dirt cheap. I use like 1 tsp/10 gallons and I have very hard water, very concentrated stuff.
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Ok good another thing to dial in! Not sure why I was using citric acid after running out of GH last time. Maybe it was in the cupboard 
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I did not know that it had that other crap in it. Good to know!
I am having this same issue. I am using ro water from a aquafx 4 part system. With innovating plant products line which is very similar to general hydro, as well as potassium silicate, and advanced nutrients concentrated ph up. I mix the silica first, cal mag second, then micro, and then add the rest. My ph still swings and was before I discovered silica, also I get a foamy slimy coating on the edges of the res and air stones. I also am concerned about not being able to leave for a couple days with no worries. The Sea green is probably similar to sea storm, that I have. Its a combo of seaweed, kelp and humic acid. I don’t use it past stretch. My veg res is not suffering from the same issue. I tried cutting damn near everything out trying to get it to stop, and cant figure it out. Hoping someone with more experience that us has an answer that can solve this for anyone else having the same issue. This is my favorite setup so far and I have tried them all, except flood and drain.
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this chart is way off. I have been using their line for 2 years now, and have made some changes. If I fed that way it would be 2.4ec. I also completely cut out the black storm, was dying everything black, hard to diagnose roots issues when doing dwc etc.
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Maybe you can test out completely cutting the seaweed additive and silicate out before I get back home and reboot my setup and let me know how it goes:wink:
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I personally am just using a pump to keep the res water moving as I said, but I can with see DWC needing the air stones etc. Apparently anything organic is going to cause a problem… especially with the oxygenated water giving them a super ideal environment to flourish in.
I would clean the crap out of my system if I was you, trying to completely get rid of what is causing the growth as this is definitely bacteria as far as I know, which can easily cause PH probs from my limited DWC experience.
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Sorry this system is a dtw in coco with airpots. I should have specified, I have ran these nutes on every medium so far and just spent the 2 years on rdwc. I don’t use the sea weed in flower and the stretch, and the silicate was something I only discovered a couple weeks, ago while trying to solve this issue. Before I was using Advanced concentrated ph up diluted at 20ml/250ml. I give some h2o2 every few days or when I remember lol, Doesn’t seem to help. info@innovatingplantproducts.comery frustrating as this is my first grow in a dtw coco setup, used coco before years ago and treated it like soil smh haha. Now with multi feeds and other things dialed in, i’m killing it. Except for this issue. I just emailed Innovating plant products to see if thy can offer any more guidance. I am flushing now and chopping Saturday, but have my next round to take over right away
Also I would definitely run air stones if I were you, More dissolved oxygen is great!
Ok thanks for clarifying.
If I were you I would cut out the 2 products mentioned above and it sounds like even running a circulating pump in the res is unnecessary from what others have said. I would stop running air stones at least to test and see if your PH stabilizes.
I really don’t think air stones are necessary in coco DTW… I think we are already pulling a huge amount of fresh oxygen into the root zone each watering as the excess nutrient solution drains out of the pot it is naturally pulling fresh air to the roots from above as far as I understand. Could be wrong. Anyone else care to chime in on this?
Anyone else run airstones with DTW?
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Guys - if you are running ANY kind of hydro - get rid of ALL organics. Dont use anything that has organic anything in it.
Try something like Jacks 321 instead. Every single nute I have tried that had ANY organic components caused wild PH rises in my systems. Jacks321 is the only one that works.
Also, test your water like I suggested above to see if you have the alkalinity issue. That will also drive your PH up.
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Thanks - yeah this is my plan when I am back on the same continent I grow on. 
Reinforcing the suggestions above for @ShuswapSmoke
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You may want to take it a step further and run a specifically sterile reservoir, that is, adding bleach and H202 to prevent anything that isn’t roots from growing in your reservoir. Both bleach and H202 dissipate quickly so you’ll need to re-apply every few days. H202 has the benefit of adding dissolved oxygen, and chlorine is a micronutrient. They’re both so cheap they’re practically free. A box of pool shock (for bleach) is a lifetime supply.
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I second this. I’m using pool shock in my rez now, in addition to exclusively using hydro-specific dry nutes, and my pH has been far more stable.
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DO is nice, but airstones will raise your pH. I avoid them completely because they take my tap from 5.5 to 6.5 in less than 24 hours. A small pump in the rez recirculating will keep the water from going stagnant, and the drips will pull enough oxygen into the coco as you water.
Just my .02$ but I’d avoid air stones.
Also using chlorine etc. instead of organic stuff seems to really keep the pH more stable. Im using Zone right now, but a guy I talk with on another forum adds 1ml of Clorox per 10 gallons of water every day to his rez and has good results.
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Thanks, but I am already running a low concentration of chlorine (pool shock) at roughly 1 PPM. Plus, Im running AAA aeroponics, drain to waste, so roots never touch my rez water.
That low level of chlorine is working because Im running Jacks321 with nothing organic in it. Plus, Im running drain to waste, so no roots to mess things up in the rez.
In the past - when I was recirculating especially, and running all the different nutes that I tried that had some sort of organic component - Advance Nutes PH Perfect, Mega Crop, Fox Farm, and GH trio - no amount of chlorine or copper or anything else I tried was able to keep the bacteria/algae in check.
I added concentrations of copper and chlorine way beyond what it typically recommended and used. The concentrations were sometimes high enough to severely damage the roots, and it still could not keep the crap from growing and making my PH go nuts.
Now that I have ditched ALL organic components, including CalMag that had some organics in it, I am able to control PH easily, and get by with very little chlorine. In fact, I only add the chlorine once when I re-fill the rez. Then I dont add any more until its time to top off. Thats usually 5 to as much as 9 days depending on my flow rate, but can be as short as three days for a short time very early in a grow.
Thats a good point even so. A little chlorine or H2O2 is good insurance. Too much will damage the roots though. Roots seem to be ok with as much as 4 to 6 PPM, but 2 to 4 PPM seems to be better fpr the roots and works ok unless you are using organic nutes.
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This tells me you have the alkalinity problem. The more you aerate, or agitate the water, the faster the dissolved CO2 leaves the solution, and the faster the PH rises. Remember, that dissolved C02 forms carbonic acid = lower PH.
Slowing down the rate of gas exchange, by using a less dramatic form of aeration, like the circulating pump, slows the rate of increase. It still happens, its just slower. That slower rate may be slow enough for the natural buffering action of the nutes to hold the PH stable.
For me, if I run at about EC 0.6 or under, the PH rises fairly fast, but above that concentration, starting about EC 0.8, it slows down a lot.
I am also using a circulating pump in the rez, but I only run it 1 minute every 20 minutes or so. Just enough to prevent anaerobic bacteria from growing. I used to have aquariums, so Im still paranoid about anaerobic bacteria 
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My apologies for the confusion, I was referring to OP when touting the sterile res.
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