Noticing my first real drop in PPMs. 237 now. My flow out is 5.9, but my return flow is 5.8. That tells me the plants are using nutes and releasing hydrogen ions which basically is the equivelant to a small dose of PH down. Awesome! ha ha, If they weren't eating, I'd have hydroxide ions being released, which is what fuels the swing, or like a small dose of PH up. Right?