HELP!
My Solana seems to be crashing and I am not sure why. Everything has been going really well, but over the last fwe days things have been going down hill fast. All of the params are as follows:
Ammonia = 0
Nitrites = 0
Nitrates = 0
Calc. = 420
Dkh = 11
Phosphates = undetectable
Temp = 77.8
20K 400 Watt halide = 4 months old
I do weekly 5 gallon water changes with RO/DI water and use reef crystals. The RO/DI shows no phosphates and I use a phosphate sponge in the aquarium. The Solana has been running for almost 18 months. I try to clean out the back chambers (as best I can) every 6 months. The tank has a fairly light load including a firefish, Pygmy angel, and a spotted mandarine (he eats frozen and flake foods). I also have a number of SPS corals and frags, mushrooms, zoas, and pulsing zenia.
About a week ago I lost my clam virtually overnight, followed by my pink monti cap, and my green slimer. This morning many of the zenia have release from the stock and are floating around the tank. Not individual polyps, but the entire head.
Any help would be appreciated. I hope that I have included enough info.
Please help.