Bleaching SPS- temperature?

[Mrbeachbum2]

My tank temperature rangest from 78.5 to 82-82.5F. I have recently lost 3 and soon to be 4 nice sized SPS frags due to bleaching. What would be the cause? Temperature? I have slacked doing water changes (once per month) and the fish and other corals are extremely healthy.

[Gary Majchrzak]

83F (alone) shouldn't bleach SPS

[InsaneClownFish]

I agree 83 shouldn't be an issue, but rapid changes are. If your reef is 78 and then hits 83 within an hour, if other parameters are off this can be a stressor.

What are your other parameters?

[dzhuo]

What would be the cause? Temperature?

Unless the corals are subjected to a constant temperature in the last 2 or 3 decades (or more), the cause is most definitely not temperature related. Swings within the thermal stress threshold don't matter as well and you won't be able to create the type of swings in the wild where most corals have adopted through millions years of revolution. Temperature (+ swings) normally do not induct any stress response from most tropical marin animals.

I would look for other causes. If you haven't done a water change in a long time, I would start with that.

[Turbovr3six]

+1 on parameter readings. When did you replace the bulbs last?