1st of all hello this is my 1st post I have been here awile though. My tank is a 39 gallon with a 20 gallon fuge/2nd tank on side of main. The main tank has been setup for about a year and a half.
When I bought this zoa colony it had green and brown zoa's all over it not too long after the green zoa's died off and the brown ones took over and started growing onto the LR that the frag was sitting on. They were doing good for a few months then they started to look like this.
They have been like this for about 5 months I have no idea what is wrong with them but none have died.
Water parameters are ok but had fairly high nitrates until recently ~20ppm