+1 for the 1 year on the DE MH
bulbs. But, I beleive the problem is the heat. I had the same issue when I was out of the country for a month and had a friiend stoppin gin once every 3 days to check and feed the tank.
Tank temp got into the upper 80's. Lost all my sps
to bleaching, the clam was faded like yours, but made a complete comeback.