I run 0dKH and have pool filter sand. I believe the sand is not completely inert as I can see my pH trend up throughout the week. This is a very small trend and easy to manage, but as of yesterday and today, my overnight pH is much lower than expected and I have had to increase CO2 to compensate. I've seen this before and chalked it up to a pH probe issues but I'm now doubting my logic. What would cause this? I grow plants hydroponically and tested pH with my liquid kit and have verified the pH is accurate with the probe.
Any thoughts? This occurred after my last water change.
Any thoughts? This occurred after my last water change.
