PH dropping fast in RDWC ?????

Hi All

Got a 360l RDWC, 1" feed and x4 3" returns in each 60l tub. So plenty of flow/no blockages. I also run a es chiller in control bucket at 20c which also provides plenty of flooming PLUS x2 airstones in each tub powered by x2 large air compressors.

The plants are healthy and no sign of root rot/stress etc BUT i am getting crazy PH drop when lights are on......

I am constantly having to add liquid silcone to increase it, lights on at night and i leave it at 6.0 and within 8 hours it has dropped to 4.6 with minimal water level drop and EC stable ?

Could my nutes be causing this, using Canna Aqua 2 part, plus bit regen a root, cannazyme, atazyme.

Cheers

Try actually using a true ph adjuster. Addiing just silicon(some will take it up and some down) will not do it, the plants absorb it and too much is not good for them.

Will do, i always thought adding a couple of mills everyday would benefit the plants, will drain off half the res and try PH up and silicone once week or less.

Cheers

I add silicon to my res's when i start them as part of my recipe but i never add anything else except ph adjusters until i change it. That way the plants get the same thing every time, all the time.

I more then willing to bet that this Ph drop happens when in flower, and not in Veg. I had the same issue with all 4 of my grows, and I use Ph perfect from Advanced nutrients. Lower your PPM, add 2ml -3ml of H2O2 (3%) , and 1 ml SM-90, per liter, as insurance against Root Rot. Lowering PMM will slow the drop, I run my DWC at about 1040ppm to 1140ppm, no higher than 1.6 EC. This regiment seems to slow the Ph drop considerably, I have never eliminated it entirely but this works for me. I use Ph adjusters as needed, abd I never take any action unless the Ph goes below 5.0.

When I make new buckets, if I don't use alkaline silica (pro-tekt) my ph will drop to low 5s, sometimes high 4s over 24 hours until after a couple days of adding ph up... then it stabalizes rock solid... maybe there has to be enough ph up to act as a buffer for the nutes lowering the ph... I don't know.

When I use pro-tekt, I generally have the same situation but not as much because the protekt already has ph buffers in it. I don't know much about nutes or ph, so this is all just my observations and guesses/reasoning from watching my own shit grow... but it seems like there isn't enough buffer in my new res until I have added ph up for a day or two... then it will sit where I set it for days on end.

If you are using tap water it may just be the off gassing of chemicals in it. My res's will always rise the first 24-36 hours but after that adjustment they stay rock steady for days also. Lots of variables. I found the biggest key to res control is finding the sweet spot for the nute ppm. My 50gal res starts at say 800ppm, when i change it 14-18 days later it will be 760-840. Find the spot where you have less than 5% swing in ppm and you will see other issues go away.

Arent PPM and PH bound inversely for the most part? I never feed over 700ppm ever in flower, never over 500 ppm in veg unless its during early flower, say first two weeks..then I up it to like 600 ppm..the ph always seems to stay just right for me, then again I am using RO water..makes life easier IMO

No. Ppm will affect ph but ph will not affect ppm. Lots of other factors can change ph without ppm changing.

that's because when you put ph solution in the main reservior it only effects that water then the next cycle comes in that was being re circulated which makes the ph drop cause it's fresh water(assuming the ph was lower in the fresh water)

Zipperhead said:

I more then willing to bet that this Ph drop happens when in flower, and not in Veg. I had the same issue with all 4 of my grows, and I use Ph perfect from Advanced nutrients. Lower your PPM, add 2ml -3ml of H2O2 (3%) , and 1 ml SM-90, per liter, as insurance against Root Rot. Lowering PMM will slow the drop, I run my DWC at about 1040ppm to 1140ppm, no higher than 1.6 EC. This regiment seems to slow the Ph drop considerably, I have never eliminated it entirely but this works for me. I use Ph adjusters as needed, abd I never take any action unless the Ph goes below 5.0.

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Yep, steady as a rock in veg, PH down made no difference, i try to keep my EC as low as i can, 2 weeks from finishing and my EC is .12 whih i have never been above.

Not got and rot there and been down the H202 road before, not sure what sm-90 is but sure it would kill any good bacteria, my plants look happy and i have dealt with the dreaded pythium with bennies after months of sterile..............

Cheers

superstoner1 said:

Try actually using a true ph adjuster. Addiing just silicon(some will take it up and some down) will not do it, the plants absorb it and too much is not good for them.

Click to expand...

Many thanks for this information now makes sense.