Interesting! Thank you for the reply back. You've given me some stuff to think about!It’s just a feeling, but I think if it is added at a wrong time and/or wrong amount / photoperiod, it can outcompete beneficial bacteria for ammonia and nitrite, and push/keep the tank in an imbalanced state, which might lead to dinos/cyanos ultimately. I also think it competes for trace elements with corals, and in some cases this could lead to growth/coral color issues. Or it competes with some type of bacteria that’s present in the system and corals feed on those. Might be a coincidence, but I’ve pulled mine after 3 years, and the skimmate is lighter now & corals have a deeper color. I’ve tried dosing no3/po4 before, but I think I still was mainly feeding the algae in the fuge with that approach.