DWC purple stem and ph problem

I apologize if the answer is somewhere in this forum, but I have yet to find one that can answer my concerns. So this is my second DWC grow and I have 4 clones ranging from 6 - 8 inches under a 400 watt mh light with 3 fans to help control high temps in my tent. On average it is about 84 degrees in the room, but the res waters at a consistent 72 degrees. For some reason the stems on 3 of the plants turned completely purple with the last one not to far behind. They are each about two weeks old. I have come to understand that if the ph is consistently dropping and the res smells off that it may be root rot, but if it smells off and raises that its an algae problem. The algae problem seems likely because in my absent mindedness I forgot to cover the res water from the light efficiently. The problem has gotten so bad that one of my clones has already been forced into flowering under 18 hours of light. From all my work asking around I found that people saying that hygrozyme works well for treating either problem. So recently I bought it and have been using it with a root accelerator for a couple days now. My real concern is am I going about fixing the problem the right way? and is it common for the PH to fluctuate so far and fast to basic after letting the plant soak in it for 30 mins.

Potassium deficiency, is often displayed through reddish/purple stems. If they are feeding in veg pH should be RISING.
There is a problem with their feeding. If it smells "off" as in stagnant then it is likely low in dissolved oxygen. (DO) For
maximum DO in a res/DWC 65-68 is the target. I'd recommend dumping the res, and remixing a new one, with some H202.
(I use 29% @ about 1.5ml/gal when they're younger.) If the roots are brown, it MAY be root rot, but sometimes nutrients stain the roots.

Hygrozyme is useful, as it breaks down dead root mass. I would recommend that about 3 days after adding the H202, as it usually dissapates
around 3-4days. I believe I use it @ ~8ml/gal.

How big is your res? Also, you have 4 plants in a tub I'm guessing?
The rate of feeding may be high, although that would make pH RISE.
The larger your res, the more stable your nutrients.

Each are in their own 4 gallon res. I cleaned my system and changed out the res earlier today. That and switched out the old air stones for new bigger ones. The PPM for each was about 360 give or take 20, but I just put in 5.7 ph water with hygrozyme, root accelerator, and super thrive for now. I'd have to get the h202 some time tomorrow. 3 of the plants do show a little sign of nute burn at the tips. Also the new leaves are starting to show chlorosis.

TheKbKing said:

Each are in their own 4 gallon res. I cleaned my system and changed out the res earlier today. That and switched out the old air stones for new bigger ones. The PPM for each was about 360 give or take 20, but I just put in 5.7 ph water with hygrozyme, root accelerator, and super thrive for now. I'd have to get the h202 some time tomorrow. 3 of the plants do show a little sign of nute burn at the tips. Also the new leaves are starting to show chlorosis.

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So about a week after all this I am pretty sure all my plant are about dead . their leaves are starting to turn brown and the last remaining healthy plant took a dive for the worst and the stem is covered in purple. The PH is still out of whack and i dont have the slightest clue why this all happened. My last grow never had such terrible problems. I'm about to kill them off and start all over again. Any ideas to what I can do to improve my set up?
18/6 hours of light
400 watt hps/mh light w/ digital ballast
4 5 gallon dwc buckets
3 fans (1 exhaust, 1 osccilating, 1 for cool air)
General hydroponic nutes
root Accelerator
super thrive
hygrozyme
Ac Unit

Common things being common, first PH. How do you measure it?

People love cheap ph instruments but accuracy is vital. High Rez temps never bother me, I use bleach. But slime and rot etc are noticeable so if you don't have mega issues with that then I'd look at PH again

Now, nutes. Purple stem? Phosphorus is my first culprit, or low temps, but the later is not your issue as your tent temps are 80.

Verdict Ph or Phos!!!

sbirch said:

Common things being common, first PH. How do you measure it?

People love cheap ph instruments but accuracy is vital. High Rez temps never bother me, I use bleach. But slime and rot etc are noticeable so if you don't have mega issues with that then I'd look at PH again

Now, nutes. Purple stem? Phosphorus is my first culprit, or low temps, but the later is not your issue as your tent temps are 80.

Verdict Ph or Phos!!!

Click to expand...

I measure my ph with a regular general hydroponics liquid ph tester(roughly 20$). I had a hannah ph tester, but IMO the thing sucked and is as good as trash. My nutes usage followed directly what the directions said on it. Like I stated above I use superthrive, hygrozyme, root excelorator, and general hydroponics nutes (floramicro, florabloom, and floragro). I was thinking of getting Silica blast to use in conjunction with the other additives, but I'm not quite sure if I should be spending my money on that or something that would be more useful to help my problem. I assumed that any nutrient deficiencies would be covered with this regimen already, but I must be wrong. My res temps are usually around 72 degrees. What in your opinion should I add to my regimen to make it more balanced and efficient so I wont run into this problem again??

And on a side note the PH IS a problem, but I don't have the slightest clue why. No matter how much I seemed to clean my systems out and use h202 to try and kill any algae or pythium that may be causing the PH to fluctuate so fast and far to basic ranging from 7-8. it never seems to stay at a constant safe level for the plants. I understand that the ph will naturally change over time, but I don't think its safe to say that the PH naturally shoots from 5.7 to 7.5/8 within 30 minutes of sitting in the new nutrient solution.

what are you using for ph down?

guerrilla medic said:

what are you using for ph down?

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General hydroponic PH down(Acid), its the whole GH liquid ph testing kit. Comes with a dropper, sample tube, and ph UP/down.

i would switch to advanced nutrients ph down and invest the 21 bucks it takes to get into a milwaukee ph tester on amazon. those test kits are ok for drain to waste in peat mix but for dwc its best to have a meter. i would use the general hydro base nutes ONLY at an ec around 1.0 and adjust from there. i personally use the micro and bloom only with great results. purple stems are phosphorus deficiency. high ph will cause this. too hot of a mix can cause lockout as well. do you have any idea what your ec is?

My EC for my plants was around .9 to 1 However, two of them are dead now and I'm considering to kill the last two and start fresh. Thinking back I'm pretty sure the temp in general for the room was to high and that's what helped progress the ph problem which caused the nutrient lock out and deficiencies. It's getting to be a bigger problem and temps are only rising since its starting to get warmer where I am right now. So i guess Ill get a new AC unit/dehumidifier when I can and then start fresh with a sterilized system.

All in all Thanks a lot for your guys advice. hopefully ill get it right next time