240 gallon tank, 1 year old started with dead rock and live sand. Chaeto, protein skimmer,.8 bulb Sunpower 8" above water run 7 hours all bulbs. I feed 4 times/day frozen and some pellets. 4 large fish and 10 smaller ones. I have been losing sps recenlty to STN and RTN. Things start to look okay and then i will lose another acro. In the past I have run much lower alk, around 8-9. Should I do a series of water changes to get it down along with my PO4 to help or should I leave this be? It seems that the frags I have had for 10 months are the ones that die and not any new additions. Also, when I do not dose anything the levels seem to not move at all. I tried dosing Kalk to bump my pH to increase growth and it just increases my alk levels since the corals don't seem to be growing. Alk= 11dkh Calcium= 470 Mg=1470 Nitrate =2.5 PO4= .18 I am on the end of battling cyano and dinos. Dinos are gone but cyano still comes back in the sand between water changes. My PO4 has been high for about 2 months now. I am wondering if the changes in PO4 have been the problem?