[sammy318]

My tank went from 78 to 80 degrees in about 12 hours when I put in 250 watt halide lighting. Does anyone have any advice on what to do to keep the temperature down, or do you know if I need a chiller? Would really appreciate some help. Thanks. -Sam

[Reefland]

Actually, I think 80 is a great temperature, 78 seems a little cool to me. I like my range of 80-82.

[charlie]

I think 80 is OK, although, I have read where some folks have been keeping their tanks under 80 degrees lately. A couple of fans blowing across the surface of your tank or your sump will help quite a bit. HTH

[Poseidon]

I had to run a chiller with a pair of 250's on my 90. It really depends on if the room has AC or not though, if you cool the room into the lower 70's then I don't think you will have an issue. If you don't have AC, then YES it will be almost mandatory. (At least in my experience)

[bguile]

How close are your lights to the water? I used to have 2 - 250W MH on a 90G inside a closed hood with a single vent fan. The lights were approx 8" off the water and if I left my sump area vented, the temperature never went above 82 degrees in the summer.

[rjs5134]

Nice to see a fellow NJ member. I don't have A/C and live in a moderately heavly wooded neighborhood that doesn't usually get too hot and I still had a poblem. August of 2006 while on vacation my 2X250W MH's, mounted 9" above the water surface, raised the water temp to well over 90 degrees. Even in winter my 65 gallon tank fluctuates between 79 and 84 degrees. Now the chiller keep temps in a 2 degree zone.

[razorfingerz]

you can find a way around a chiller.. ive got 2x 250W MHs and i dont even use a fan!!! mytank is steady 80 degrees

[Ratpack]

This same issue has driven me more towards T5 lighting but I am still partially considering MH. The main will be a 75g and my house is air conditioned, but in the summer it is still about 80 in the house during the day. Could I go with 175W MH and vent the hood as well as fans on the sump? A chiller just isn't in my budget right now.

[bguile]

Reading back on this thread, I don't see where you mentioned how many lights you are talking about. I'm guessing we all assumed 2 based on the "normal" dimensions of a 90G. I have a few more questions:

1. What is the normal temperature of your tank without lights?
2. How many and what type of pumps are you using?
3. What other items are in the system that contribute heat?

Also, what is in your tank? If you're not keeping SPS at the bottom of your tank you may not need 250W or 175W.

You could also consider what has been said previously. Just about everyone's tank is maintained around the 80-82F temperature. If your lights aren't taking the temp above that, I wouldn't spend so much energy worrying about it.