pH'ing aerated water

[Gingerbeard]

I'm not going to tell you my pH numbers for this thread because you people will go off on a tangent, so mnyahh! That's not part of my question.
Just took to dropping an air stone in my water for an hour+ before adding nutes and pH'ing.
I recall a while back ago something about aeration affecting the pH level of water/nutrient solution. Since aerating, I am using a little more pH down to get my numbers.
My plants look like they are trying to have a pH issue with purpling wanting to happen on the lower fans. Pictures won't show what I mean. A daddy knows his girls.
Does aerated water/nutrient solution need different pH consideration than tap or off-gassed water/nutrient solution?

 

[apacin0]

I use tap water and two air stones. I always have the water bubbling except for when I'm mixing (well I use the bubbles to mix for a few seconds after each drop) and testing, as moving water throws PH meter off. My tap water is low ppm lake water from a mountain on an island in Alaska. However they add soda ash which increases alkalinity to reduce pipe erosion and chlorine. This makes it very high PH. I've been letting my water sit bubbling over night before PHing the last two times. I think the best approach is to add nutes (neutralizes the PH) and bubble over night. Then PH in morn. I have no PH issues that I know of. I'm using unbuffered coco/leca and never test runoff nor adjust PH twice. My res has been lasting half a week maybe. There are so many variables, we could use the same processes and material and have different results.

The other thing is water temp. Are you running just the cold water? An hour+ should warm it to room temp with air flowing, but could it be different than leaving it out a while to off-gas? Colder temps could explain purpling maybe. Not sure if that effect is from just air temps or both air and root zone temps.

 

[Gingerbeard]

I'm in SoCal. We don't do indoor temperatures that cause purpling. As if!
Water is room temperature that has been sitting for a couple days. This is from pH. I've been doing the same thing for a few years. Only the stoning is new.
Thinking on it, might be I need to calibrate the ol' Blue Lab.

 

[Bluey]

Yes. It needs monitoring. But your changes in pH may not just be related to aeration, eg. A cloning bucket will suffer from dropping pH if you have enough roots immersed in the solution regardless of aeration. No roots in solution and it goes the other way, up up and away

 

[Gingerbeard]

Been thinking on that, too. In my grows, the only things that change are the strain and season. I guess meter calibration, too.
The only change I have no control over is if my local water people change which of Satan's toilets they supply me with.

 

[golfnrl]

My autopot system runs off of a 12 gallon reservoir. I switched from an air stone to a small pump in the rez set to run a few mins several times a day, The stones made it difficult to maintain a steady PH. After some reading on here, I switched.

 

[Gingerbeard]

What I read in this is quantity. If I am not mistaken golfnrl you are aerating, just not overdosing. At some point the water becomes saturated with O2. So, maybe, after a few minutes, the water has as much as it can handle? An hour is too much but a little over time does the trick?

 

[bdeegan]

I use air stones to adjust the ph of my acidic well water. I think it has more to do with why your ph is low as to how much affect it has. My well runs low ph due to high co2 levels from decaying plant matter (it’s in the middle of the woods!). By bubbling (adding o2) a bucket for 24-48hrs I take 5.3 to 6.7. It does tend to drop off (but not back to the low 5s), so I always keep a bucket bubbling when the girls are thirsty!