Fluctuating temperatures actually benefit corals
 

Here's a link to an abstract of the study:

http://onlinelibrary.wiley.com/doi/1...199.x/abstract

From the abstract:

"In all treatments, the maximum dark-adapted quantum yield of photosystem II (FV/FM) of the larvae was ∼49% lower than that of adult corals; FV/FM in the larvae also differed among temperature treatments, with the highest values in the fluctuating treatment."

The fluctuating treatment that the article refers to is varying the daily water temperature between 21C and 28C.

Mitch

For those that are interested, here's another good article - (this one's free) - discussing the varying temperature and salinity conditions that our corals and invertebrates come from:

http://www.ronshimek.com/salinity_temperature.html

Mitch

I saw a lady's tank who had no heater, the halides heated the tank i the day time and the tank would cool to in the high 60'sF in the winter at night. It was one of the nicest sps tanks i have ever seen.