I was asked an interesting question the other day about ATS's and nutrients or should I say lack of nutrients that an ATS is capable of achieving. If your nutrients get too low your corals can suffer as they do best with a little nitrate and phosphate in the water and an ATS is more than capable of reducing the nitrate in particular to very low levels. So the question to me was, what do you do if the nutrients get too low? Well, you have 2 choices IMO. You can increase the amount of food you feed your fish and corals or if you don't wish to do that simply reduce the time the lights are on the scrubber. Reducing the lighting time will/should reduce the take up of nutrients so you should be able to fine tune your TAS to hit the sweet spot between the amount of food you need and the lighting period of the ATS. I feed 3 and often 4 times a day and my NO3 has dropped from 25ppm to 2ppm. However, my PO4 is still a little higher than I would like but a little PO4 media in a small reactor should bring that down to a more acceptable level. Any thoughts on the above? Do I have it about right or am I missing something from the above?