you really need to flush the plants with at least one gallon of water per gallon of soil. the 1 gallon in a 3 gallon pot is not a flush. a flush is excessive amounts of water leaching mineral salts out of your medium. you want to get your soild back to basic. take as many variables out of the equation that you can, or simplfy things.

your pH lowering that much isn't horrible. just bump your nute mix up. you can run it up to 6.8. then check runoff. and don't so much worry about runoff pH if your plants look health. do they look healthy?

are you feeding normally with RO water? if so you need to use calmag (or molasses) and get your PPM to ~200-250 and THEN add your nutes.

i wouldn't feed anything until you figure out what the problem is. i would use water (and if RO calmag or molasses).

dolomitic lime takes time to break down, and is a long term solution. your would be better off using hydrated lime. but be careful because too much is toxic and it can burn your roots.


-shake