Yesterday morning I dosed suppliements, iodine and strontium (both salifert) and reef booster, turned my skimmer off and went to work. Came home and all the corals were shrivelled up.
My tank is approx 170L, running a deltec MCE600 hang on, 2 eheim compact 1000's for flow, and a canister filter for filter wool and resins, and at this stage a double t5 unit.
My thinking was that turning off the skimmer for the whole day, meant less oxygen in the water.
Anyone can help more?