[GpsFrontier]

Hello jhinkle,

I also discovered that the RO process removes all PH buffering leaving only the PH buffering provided by the nutrients that are added.

RO water is fine, the buffers in the nutrients is all you need. Assuming the nutrients have pH buffers. If not they should.

I also discovered that adding O2 to the nutrient solution -- via a bubblier -- tends to offset the PH in the UP direction.

Where did you hear this. Using a bubblier has never changed pH. If it does you got bigger problems because the air your breathing has toxic levels of chemicals in it.

I've been adding PH down but that is NOT addressing the buffering issue --- just chasing the PH dog's tail.

Buffering isn't an issue as long as your using quality nutrients with pH buffers. Something is wrong, either something foreign has been introduced into your reservoir, or your misusing or mishandling the nutrients.

I know that a buffering solution is made by mixing equal and opposite amounts of acid and base --- so that a small shift in PH does not produce a big swing as I am experiencing.

Don't go concocting your own chemical additives, that is unless you enjoy problems.

If your pH is drastically rising daily, even on fresh nutrients, something is wrong in your reservoir. To figure it out, start with the basics. Forgive me if you already answered some of these questions, but it's much easier and less time consuming to just ask, than it is to go through the whole thread looking for a few words here and there.

1. You said your using RO water, but has the RO system had regular maintenance done and filters changed?
2. Is RO water all that you use? and have ever used? As an example using mostly RO, but adding some tap water because you couldn't get enough RO water from the RO system in time.
3. Have you tested the RO pH? Right from the tap without anything in it, and from the same sample of water daily for a week to look for pH swings in the water supply?
4. What nutrients are you using?
5. Have you used any other nutrients on those plants?
6. How exactly are you mixing the nutrients? Both what you add and how much, as well as the process you go through when mixing them.
7. Did you add anything other than the nutrients to the reservoir (now or ever)? Any additives etc. etc.. (list everything that has now or ever gone into the reservoir water)
8. How are you checking pH? (pH meter, pH drops, if drops what kind)
9. What are you using for pH adjusters?
10. What does the water in the reservoir look like (is it translucent/clear or clowdy)?
11. What does the water in the reservoir smell like? Does it smell musty or moldy?
12. is there any foam on top of the water?
13. Is there any white powder looking residue at the bottom of the reservoir?