Lighting is fairly low. 2 NO white actinic and 1 NO blue, tank is 18" deep. I was told that the polyps wouldn't need strong lighting and they haven't lost any of their colour (symbiotic zooanthe?). Do you think lighting might be the cause of them shrinking? I have had them about six months and for the first 4 months they looked great but over the last few weeks they have shrunk considerably. Is there anything I can feed them with? The larger polyps (freebies!) appear to have a mouth and can engulf quite large chunks of meat but these are different.
Tank is as follows -
ammonia = 0
nitrite = 0
Nitrate = 0 ( could this be the problem, Is the tank too clean?)
Calcium = 400
oxygen = OK, can't remember exactly
Phosphate = 0
Any help would be greatly appreciated!