I am new to SW hobby and have just purchased this 6G nano system from craigslist. The seller said that his hammer coral was huge before, but then started to shrink and now it looks like it barely comes out. I've checked all chemical levels and they all read fine. I am not feeding it, weekly CW 20%. For light i've got one bulb of T5HO 460nm Actinic and T5HO 12 KK Power White and run both of them 8 hours a day. I don’t have any fish and i will also post pics of closest corals. Please help.