Me, heater set to 78, usually sits around 79-81.

Temperature swings are bad but higher temps shouldn't really kill anything that isn't a deep water or temperate species.
Most reefs/dives I've been on the temps are 84 to 86F and things are living and thriving.

Like I said before, I follow Ron's logic with respect to matching the natural reef parameters. It is what evolution has prepared the animals for I hope.

Temp swings suck, but they happen, and most healthy corals should handle it. I went a long time one summer bouncing from 80 to 90 daily, and only lost one species of acro (8 frags of it). Everything else was fine, although perhaps a bit more brown..

24.5C 25.5C (78) here
http://www.wbuf.noaa.gov/tempfc.htm
Heater is my controller and water tubing coil cooled with cold tap water is my chiller.
I run a 1/4 inch OD tube from my RO/DI inlet to the sump, and back to the P-trap, with straight valve slightly open to the fast drip.
There is a 15 feet tube coil in the sump acts as a heat exchanger/cooler.
Back to the RO/DI waste line and in to the drain. water cost for a few short Summer month in Vancouver where it rains 9 month out of 12 is nothing compare to the cost of the controller and chiller and electricity to run the chiller.


Cut water supply line to RO/DI and insert the 1/4" OD line in with straight line valve for flow control.
http://i381.photobucket.com/albums/o...IMG_0442-1.jpg
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Run the tube line to you sump and make a coil that will act as a heat exchanger
http://i381.photobucket.com/albums/o...ofIMG_0439.jpg
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Run the tube line back to the RO/DI waiste line and or back to the P trap
http://i381.photobucket.com/albums/o...IMG_0441-1.jpg
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You summer chiller is on line !
If water will get below set your heater will kick in.

I followed that logic last year and still waiting for some SPS to recover this year, the sps colonies browned out and one was full of algae that i had to cut out with skeleton chunks. So this year i am keeping it at 78 (25.5C) tops.

This small heat exchanger coil works amazingly well. My tank is 65 gal + ~10 of water in the sump. For larger tanks i would just increase the size of the heat exchanger coil.

Just an update on raising my temp to 79. Since then I've noticed increased growth on almost every piece i have. No change in color at all, but some pieces that appeared dormant for a year suddenly have grown to triple what they were.
So I'm changing my original answer to be 79F as the optimal temp :)

Have you noticed any changes in any of your fish or inverts?

Nope, the only difference is an increase in coral growth. I might suggest that my skimmer fills up quicker, but that could be from other reasons.

Hmm, I wonder if keeping my temp at 79 is why my znp grow like weeds. I have lots of frags from others that say they are slow growers but sprout new heads quickly in my tank. Could be the crazy high nutrients from over feeding though, lol. :what:

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