Grow Mediums pH keeps fluctuating

[Surfer Joe]

I am doing a bubble bucket grow and I keep a bucket with tap water and one with extra nute solution ready to add to the buckets as the liquid levels drop.
I keep an aquarium heater and an airstone running in the extra water so that when I add it to the buckets, it will be at a similar temp and have some oxygen in it already.
My local tap water has a pH of 7.4 and a ppm of 295, but after it sits in the water bucket for a couple of days with just the airstone and the heater, the pH goes up to about 8.4.

Why is the pH of the plain water going up?

The pH in the plant buckets drifts in a normal way.

I remember from science that sometimes running air through a liquid can cause some chemicals to precipitate (like calcium carbonate). Could this be causing the pH to go up?
Should I just let the water sit without air or heat before I use it?
I thought that letting the water sit for a few days would help reduce any chlorine, etc. rather than using it fresh from the tap and just adding pH down before using it.
How do you guys manage the adding of extra water or nutes to your bubble buckets between rez changes?

I hope that this grow works because I am amazed at the difference in size between the soil grown plant and the hydro grown plant. The hydro plant is about 3 times larger and it's only on its 4th week since sprouting.
Thanks for any advice.

 

[Doulovebeef]

I always keep water bubbling, it does stabilize ph, although not at the range u want in Ur case. I use ro, so mine stabilizes at 7 like clock work. Keep ur water bubbling, and add nutes as u need them. Sometimes u need half strength, sometimes u need no nutes at all. It just simplifies things in my opinion. Oh, and take off the heat, low water temps improves o2 ppm and reduces risk of pathogens in ur water. Mine stays at like 60f

 

[Roark]

Yup. I don't worry bout p.h til the last thing has been added. Then adjust p.h. don't have any idea about the swing.

 

[TxOld Dude]

Too much dissolved calcium (295 ppm)? I had the same problem, pH jumped all over the place. pH it down and in a few days had to do it again. I switched to store bought jug water and all my troubles went away. JMHO

 

[sniper]

Im pretty sure the ph in bubbled plain water goes up cause of the added O2

 

[cidd]

Yep don't PH your water until after you add the nutes they will drop it some on there own and since you're doing hydro your PH needs to be between 5.3 and 6.5 / 5.8 being best but the PH will go up and down depending on where the plant is in its growth cycle . Mine seemed to go up when plant was just starting out but after it reached its veg spurt ( growing like mad ) it was pulling the ph down daily. I had to keep a very close eye on it when mine started taking the PH down I would add just plain dechlorinated tap water and let it raise the PH some then if needed I would add some PH up and try to get it to 6.5.The plant will pull it down on its own between watering refills . Now that its in end of its flowering stage its slowed up on the PH and nutes and seems to drinking more water. Look thru this hydro section and you'll find a lot of info on the subject just don't get all panicked if you see little rust spot on your leaves fist sign of PH problems as long as you try and keep up on it things will work out mine still has some rust but is doing fine.

 

[Surfer Joe]

Too much dissolved calcium (295 ppm)? I had the same problem, pH jumped all over the place. pH it down and in a few days had to do it again. I switched to store bought jug water and all my troubles went away. JMHO

The plant is now drinking a gallon a day, so that option's out.
I did buy a water filter and I pass the top up water through that and it lowers the ppm to about 190.

 

[TxOld Dude]

The plant is now drinking a gallon a day, so that option's out.
I did buy a water filter and I pass the top up water through that and it lowers the ppm to about 190.

I feel ya there! I've been buying jug water, but like yours, mines up to a half gallon almost per day. Gonna have to do the RO thang soon. Hell, been wanting one forever anyway...