or big lights.

I meant for when the lights go out at night.

I guess it COULD be huge lighting for a 24hr fuge.

I'm usually at 78.5 lights off and 79.5 lights on. Ive seen my heater off in the dark and on in the light.. doesn't make much sense eh? I should look into a controller for safety sake.

If you don;t want to spend alot of money on a controller you can do what some of us do and have 2 smaller heaters instead of one big one!!That way if one ever sticks on then you won;t end up with reef soup!

what kind of thernometer are you using?? If it is one that you stick to the outside of your tank... NO GOOD If you are using digital make sure its a good one.

LOL Reef Soup looks and smells worse than u'd think

If your going to run 2 under sized heaters they better be small I had 2 100w Ebo heaters in my 50g + 20sh sump one of the heaters stuck on and with the lights it fryed my tank. If u dont want to spend the $150 on a controller you could put your heaters on a timmer so that the heaters turn on and off every 15 min. thats what i do on my frag tank 20g at home it works good with very little temp swings.
this is just my rambling i don't mean to flame the thread ...its just a real bummer to come home to a fryed tank (i hope this never happens to anyone)

some fluctuations in temp are normal in nature, as well as salinity. I think if you let your tank be too steady in temp/sal, when/if something does happen they are just way to sensitive. My tank temps and salinity varies quite a bit and everyone is always happy as can be (SPS, LPS, Zoa's and Anenome). Of course, I am not talking about when a heater gets stuck on and it jumps 10 degree's. Oxygen diffusion is another matter all together when it comes to temps.

Perfect stabilty is not always where it is at, you do want some movements but not wild fluctuations.
Some fantastic data can be viewed here

http://www.nodc.noaa.gov/GTSPP/gtspp-home.html

and

http://www.nodc.noaa.gov/dsdt/oisst/index.html

BTW, you can get that RANCO controller much cheaper. You do have to wire it on your own, but for most people it should not be an issue to do. Here is a good link to a supplier who will ship to Canada.

http://www.allthermal.com/Merchant2/...&Category_Code

im actually going to be selling my ranco controller soon when i upgrade to a computer controller.

a temp controler is a good idea but they are useless unless you have a chiller also. also event a ronco has a dead band so you will still get a 1 or 2 degree swing. a couple degrees is fine, mine at onepoint used to swing about 6 degrees and I never had an issue.. now with a chiller and a heater I only get about a 1 degree swing.

Why is it useless without a chiller?

Say I have 4 heaters and hook them up to a controller, would that not help keep the temperature more constant even without a chiller?