pH rising quickly, is this normal?

[occg.hydro]

I've looked around the site and can't seem to find a whole lot of info on the problem I'm having. My res is 18 gal, RO water w/ botanicare Cal Mag, advanced nutrients sensi 2 part, piranha, and fulvix. I'm running a 9 bucket drip system using hydroton pebbles. The res temp stays around 76, 550ppm and I'm aerating lightly, but not too much. I just started my clones yesterday and my pH rises around a full point over 10 to 12 hours. Is it normal for it to rise this quickly? it doesn't seem to stabilize until around 7.2 - 7.4 but I've been dropping it back down to 5.5 - 5.6 and the first time I cycle it through the medium the pH starts to rise really quickly again. From what I've read It seems like it's best to try to maintain a pH of about 5.6 - to 6.5, is this correct? What's going on? I let the hydroton soak in bleach and water for 48 hours and then washed it 3 times really well. I made sure to run plain distilled water through my whole system. Could it be that the bleach buffered the pH of my medium? This is my first time with hydro. I can handle a plant in soil, no problem, and I thought I'd done my homework before starting on hydro but I obviously have plenty of learning to do. Any advice would be great. Thanks guys!

 

[massproducer]

Are you using rockwool?

 

[MickFoster]

I have that problem evertime I start a new grow in a drip system with hydroton pebbles. It straightens out after a couple of weeks. I know you'll get different opinions regarding hydroton effecting the pH - but if it's inert and pH neutral - why do people always have the same problem with the pH going up a point overnite. Don't worry - it'll straighten out - always does for me.

 

[KADE]

5.8-6.2 for vegging. Rapid root growth and algae growth will both cause ph to go up in a solution. Probably one of the two. Once the plants are big enough where they are using a few gallons a day it'll be the opposite... dropping rapidly.

 

[KGB30]

Do you have hard water that can cause your Ph levels of the water to go up over 7 GPG

 

[occg.hydro]

wow, thanks for all the input! I'm not using any rockwool in the system. The clones I got were started in coir. They were transplanted two days ago, so I would expect them to be sucking up juice pretty quickly and trying to pop out some new roots. I use RO water with a starting pH of 6.89 and a ppm of 5. I used translucent blue 1/2" tubing for my return lines and there are a few that aren't painted black. I'll tape those up, make them light tight and give the babies some time to level out.

 

[fishcabo]

I have the same problem with my hydroten in an ebb and flow. I just plan to lower the ph every day for a couple of weeks until it stabilizes. Remember, different nutrients are more available to plants at different ph's. It is good to have some flux as long as it is reason. Totaly controllable, totally not a problem that can't be easily remedied, just part of growing. Good luck

 

[occg.hydro]

It's day 4 now and it looks like the pH is starting to level out a bit. I've been tracking everything in excel so that I can chart ppm, pH, temp's, etc. I adjusted the pH back down to 5.64 last night at 1:30am before I went to sleep and at 11:30am, just before the night cycle, the pH had only risen to 5.72 and the ppm went up just a few points. I had expected it to rise a bit more so I adjusted it a little on the low side, but it looks like after it cycles a few times and the air pump starts aerating the res again it'll be right back to the ideal range. Thanks for all the great advice everyone!

 

[allgrownup]

add enuf ph down to drop your ph to around 4.8 to 5. then see where it stabalizes. you can always add some tap water to bring it up. contantly changing ph stress's the plant. try to establish/balance it as early as you can and then it should maintain. i find that everytime i dump the res, i can add a little ph down and then check it later and its back up. i think it takes a bit to saturate and stay down. mix it well also