Hello, I was hoping for some pointers regarding my tank. Pretty much the following Corals are not doing as well as they used to Blasto - All heads quite small. pulsing Xenia - Fully recessed for weeks BTA - somewhat recessed Torch - Somewhat recessed Chalice - Slight bleaching GSP - Doing fine Zoanthids - not all open Now I can tell you that I've not done a water change in months which is what I suspect is the problem. My tank parameters are NH4 - 0 NO2- 0 NO3 - 0 (I can't detect any using the colour kits, everything else is a Hanna Instruments checker reading). PO4 - 0.05 DKH - 10 Salinity - 1.026 MG - 1200 Calcium - 530 (I know this is high, I'm trying to bring it down). PH - 7.9 Temp - 24.0 Lights are XR30 Pros at 30% power for 8 hours a day. There is a Skimmer running on the system as well as Phosgaurd reactor, Carbon Reactor and a ALR15 Algae reactor. I'm assuming given my crucial parameters are fine that the tank is starved of a type of trace element however I have no idea how to test for this? I am dosing Iodine and Reef trace by Seachem twice weekly as well as 10ml of Red Sea NOPOX daily. Any help would be great.