Yes sir, that is the one. I used to run ULN, but as you can see what happened above there is not much room for error unless you’re doing something like Zeovit. The corals get well fed, and are able to tolerate the very low PO4. Now, I try to keep it 0.03 to 0.2 ppm. Above 0.2 and there’s more algae to deal with, but it depends on the tank and the system. I’m ok with it in that range and I try not to chase it too much. Honestly I like it above 0.05 and under 0.15, but if it drifts a little I’m okay.
