Toadstools not opening polyps since months

[DEGREGORIIS]

HELP ! I don't get it. My water chemistry looks ok. All values(incl Strontium, iodide, etc) are within the limits, PO4 is 0.08 NO3 is 5 to 10, Salinity 34, etc. But my toadstool corals are not showing their polyps since months. So, my question: what could be the cause of it ? All comments are welcome as I will check them one by one. One say my lights are to intensive, other say my centropyge are bothering them ( but I have 5 BIG toadstools) and only 6 small CG's... My tank is 4 meter and I have about 30.000 L/hour water displacement. Total volume is 1500 L netto. Using A Deltec skimmer good for 3000 tanks. SPS and LPS do well, my Zoa and Paly's are not 100% neither.

 

[Fishboyz]

what kind of flow are they getting? I have my toadstool under high flow and he loves it. Thing about toadstools is I believe they shed a thin layer of skin every now and then and the flow helps blow it off as well as preventing detritus building up on it