pH on the rise

[noobie97]

Okay so the water in my reservoir is climbing faster than it should.. After it is pH'ed to about 5.8, within several hours it has climbed back to 6.8 and even to 7.4.

I'm running two ebb and flows and they both are having the same problem, the res that supports the bigger plants typically has a higher pH than the other.

Each 55 gal res (filled to 50 gal) has twenty plants, about 6 weeks into veg. The nutes are H&G, the entire line minus the amino acid and nitrogen booster.
H202 at 15ml/gal..

I was using RO water but heard that CalMag in tap can help buffer the pH, so I have been filling up a spare res with tap water 24 hours before I put in fresh water/nutes to let chlorine evaporate..

Each res also has an air pump and airstone to provide some extra DO.

Lights are run 24/7.. so temps are pretty steady 68-73 humidity between 43%..
I live in a dry climate so I run a humidifier or else the humidity would be in the teens!

I've read that the airstones can increase pH, and also that plants feeding release hydrogen which in turn raises pH. But is there not a way to buffer?

Any experience or advice would be great,

 

[noobie97]

EC is around .8 to 1.0..

 

[PrairiePoet]

I had the same question as Jakester, what is your reservoir temp?

Also, CalMag is needed with RO water. And RO has nothing in it to help buffer pH, like tap does. What are you using to lower pH?

 

[StonerJ]

When I had an in ground pool a few years back, it was damn near impossible to maintain the pH when the water temp was up in the high 70's and above. Comfy yes..... but the pH would climb like crazy. I was constantly adding pH down to the pool. It's really hard to maintain pH when the water is too warm.

With hydro, mid to high 60's solution temp is definitely the key when it comes to keeping the pH in check.

 

[HiTimes4Me]

Try flushing everything with ph'd water and then cleaning your whole system and regulating res. temps....because it could be something in your medium causing the ph rise and flushing would get that out and then cleaning the system would eliminate contaminents...and like state temps. make ph rise...

 

[noobie97]

Res temps are between 60-63.. Winters are cold around here and I keep the heat off outside the flower room where the reservoirs are kept for just that reason.

But anyways, I took out the airstones and added 200ppm of CalMag. seems to have taken care of it, I haven't had to pH yet three days after changing the res...

 

[noobie97]

Yea man couldn't tell you, I think I'll be on the safe side and just leave them out!

Thanks guys..!!

 

[Laid]

I know you solve your problem but you said you use h202 at 15ml/gal if it's the 29% I think thats hi IMO. I use 2ml/gal the day before I do a rez change as a preventive