PH problems

Hi, i use House n Gardens nutes. I have RO water. I use a run to waste system. My PH is all over the map, i have a comstant read monitor, when the nutes go in the PH will be around 6, then the next day it will be at 4. I add PH up, get it to 6, and within 24 hours its back down to 4. I have 3 seperate 55g resevoirs and they all read about the same. I am adding cal/mag 100ml figuring this would stabilize but its not helping.
Per HG i dont run an airstone, just a circulator pump to keep the nutes mixed.
Any advice?

Honestly this seems to be a common issue with H&G nutes. You might run through the H&G thread to see if anyone came up with a best solution (or just change nutes).

As a bandaid, you can add Silica supplements instead of pH up, at least thats a useful addition (the potassium).

To pinpoint H&G as the cause you might want to just grab a small set of bottles for another nutrient and see how that works for you. I highly recommend GH Flora 3 part with Calimagic since you are running RO h2o.

Best of luck and happy growing.

Yeah i nevet had problems running the flora series, ive only been with HG for 9 months