Hello, I'm at a loss. I'm still relatively new to this and so not really sure what is going on! My tank is about 9 months old, generally been good although did go through a period a while back where my corals started to look really bad. Am through that now and thought i was doing well but in the last few weeks i've lost 4 fish. I've checked all the things i think i should be checking and aside from Nitrate being 12ppm ( which i didn't think was too bad ) i can't spot what could be wrong. Rather than be told what to do, as i'm learning i'd love to hear peoples thought process about what could be going on so that if it happens again i'll know what / why / how. So, what would you be looking for? What would you test first? What would you be looking out for? I have a 200L tank - 2 clown fish, 2 fire shrimps, 3 turbo snails, 3 narcissus snails and 4 yellow tail chromis, 1 chalk goby. Help!