my ph wont stay put

For some reason ,my ph in my 10 gallon resevoir wont stay between 5.78 and 6.2.I take it down to the appropiate number,and the next day its right back up to 7.35 or something no where i need it to be.I am using r20 and i make sure the ppms are right in it before i add my nutes.I use less than what the directions say on the back.I have a sumbersable pump that has a T at the end of it so the water is constanly circulating and i have 2 huge airstone that keep it airated.My growing mediums are just rockwool cubes in 3 inch baskets filled with round clay balls on a drip system.I keep my water temprature at 21 or 22 degrees celcius and my growing area temp is top 85 and low 63,humidity levels range from 27 and 50 percent humidity.It just seems that im putting way to much up and down in there to controll the ph

Welcome to hydro.

http://boards.cannabis.com/plant-pro...-question.html

your pH is rising primarily from the buffering effects of the rockwool and hydroton ... you have to pre-soak rockwool for a few days before using it, to allow it's pH to settle ... hydroton also contributes alkalinity ... I try to take advantage of the pH rise, by being able to run a little 'hotter' nute feeding :jointsmile:

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Originally Posted by the image reaper

your pH is rising primarily from the buffering effects of the rockwool and hydroton ... you have to pre-soak rockwool for a few days before using it, to allow it's pH to settle ... hydroton also contributes alkalinity ... I try to take advantage of the pH rise, by being able to run a little 'hotter' nute feeding :jointsmile:

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IR hit it: your grow media is most likely causing the fluctuation. Throw your media into a bubble bucket with some pH'ed (5.6-5.8) nutrient solution and let it bubble out. Use a weak nutrient solution (like 10-25% of full strength) and check the pH every few hours. When you go a day without the pH rising (or falling) much, you're done.

Did you pre-treat the hydroton and rockwool as directed before use? Both media need to be soaked and adjusted to 'set' the pH at 6.0 before ANY plants are introduced to the system.