I use only lemon juice and baking soda as ph up and down. works fine and I have yet to see ph drift, especially with baking soda for ph up. Seems to be self buffering.
There is a little foam filter in the "pure" autopot reservoirs, and it is there for a reason. If I don't clean it every 2 - 3 weeks, depending where in the grow cycle the plants are at and amount of water they are drinking, the filter will clog up and block the water flow. Amazing how much gunk is produced when you mix up a solution.......and my faith in those "cleaning" products........View attachment 524304
That being said, I did use concentrated vinegar to fiddle with the pH, and have since learned that vinegar is known to cause gunk or slime, to be eliminated by adding citric acid to the mix.....will give that a try and see if it makes a difference, or just just use citric acid in place of vinegar. We'll see......