I'm trying to decide if I need a phosphate or carbon reactor? I've had my 90 reef for several years now without major problems. In the last few months, i've been really struggling with brown algae on my sand. i have a great skimmer and use carbon and phosban in media bags, but don't know if they're helping. (carbon does help with clarity) I have 2 anthias and a hungry tang which require multiple feedings per day. I assume this feeding regiment is not helping. I also am trying to increase growth in my corals so i feed them too (including a sun coral which requires point feeding, and is doing great). None of my LSP or SPS have really grown much. maybe i should just cut out all this feeding? My tests: Nitrates=12.5 mg/l. Phosphates=.00, Calcuim=450, Alk=9.3, Mg=1350, sg=1.024, temp=77.5, RODI I know my phospates are showing 0.0. I've read that the algae may be converting the PO4 that is present thus the test will show 0. It just seems that I have 2 common symptoms of phosphates, even though the test says otherwise...ie algae on sand and limited coral growth. I've looked at the BRS GFO/Carbon reactors. The single unit that can hold both media, or the dual unit. Is this what my tank is lacking?