Thank you bro Thomas.
The 4 fire gobies hv been with me for 4mths now, usually when light off, they will hide at their usually place which is under one of the live rock. When light on, one by one they will come out, so far no fight btw them. You shd try again for the fire gobies, very nice schooling fish.
I dun think water changes can keep up with the sps demands. Unless u do like twice every week. Depends on how much sps u have. Just constantly monitor it. might have to add more kh and ca