How do you dissipate heat from MH?

[Chandler]

I am converting from a 55 FOWLR to a 180 this weekend and plan to convert (slowly) to a reef system. Planning with the end in mind, I want a lighting setup for mostly, if not all LPS coral. I have read thru most of the old posts on lighting and have yet to see anything on how to deal with the heat generated by MH lighting (other than a chiller :) ). I am wavering between 6, 6' VHO's or 3 175 w MH w/ maybe 2 VHO actinic to supplement. I would like to avoid the expense of a chiller if at all possible, so I have considered using 3, 4-6" fans installed directly over the bulbs blowing up toward the ceiling to pull off the heat. I'm just not sure if the fans will do the trick with the MH s. I can wait for a while on the lights, I'm just trying to get some experienced feedback. Thanks in advance for your help.

[Targus]

Hi,
I put 2 fans in the hood to help out and when it get's too hot anyway I run a floor fan across the top of the water.
I use this method on a 65g reef, it has 1 175w 10k halide and 2 actinics.
HTH,
Mike

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See my tank at http://www.homestead.com/reefcentral/targus.html

[Rinaldi]

Two 4" fans from Radio Shack work just fine for me with 2 175w mh on a 75g. I should note that the tank is basically completely open and I rarely close the hood.

[Frisco]

I have 2 175W MH + 2 100W VHO with 2 4" cooling fans on an enclosed metal hood with plexi shield to keep the bulbs cool. A 3" fan periodically blowing across the water surface keeps the temp down as low as 76F. It's really easy to control the temp with these bulbs.

400s are supposed to be just as easy, provided you can thermally isolate them from the tank well. I'm adding 400's next time I have to replace the bulbs.