MH heat and fans to cool it question

[runway1]

I added 2-175 watt MH light to my 55 gal tank. Seems to be too much heat. Question is; if I raise the lights another 3" from the water surface and then add two 3" fans, would this be enough to cool my situation? TIA!

 

[JPloman]

I had a similar situation! Make sure the fans are pulling the heat out and you should be fine.

 

[runway1]

As opposed to blowing in, you mean? I.e. Set the fans to PULL (blow outward) instead if PUSH (blow inward) - correct?

Thanks again!

 

[steve-s]

Correct!!

Cheers
Steve

 

[klam]

IMO, the fans in the hood will help dissapate the heat in the hood which is good but will have minimal impact on the water temp because the light is still striking the surafce area.

The recomended height to hang MH is about 8"-12" above the water line. Adding a fan to blow across the water surface will help cool the tanks temp by evaporation. Make sure you have fresh water handy to make up for the evaporation.

 

[runway1]

Currently, I have acrylic covers to minimize evaporation. Do I remove these? Should the water surface remain completely uncovered?

 

[steve-s]

Removing the tank cover will definately improve matters. Just be sure it is not the lense cover to the light hood as it protects it from water spray from the tank. Leaving as much open space over the tank as possible will improve gas exchange and increase evaporation which in turn will help cool the tank. If you are concerned about fish, use eggcrate material to cover concern area's of the tank top.

Cheers
Steve

 

[fishfreek]

Most of us run our tanks uncovered with respect to having something directly over the waters surface. As your seeing when you use high outputlights the heat generated can really make a difference with covers or with out covers. As Steve mentioned if your MH canopy has a cover that you not remove this. This cover can serve two purposes. First many have a UV filtering element to cut down on the amount of UV light emitted by the bulbs and the second is it keeps water spray from hitting the hot bulb causing the bulb to blow.

Other ways to increase cooling is to increase the water movement. If you can direct a PH to cause a good ripple at the water surface this will aid in gas exchange and thus increase evaporation therefor lowering water temp. If your running a sump or you can put a fan over your tank that blows are directly at the surface of the water. This will also increase evaporation cooling the water.

Be prepaired for upward to 1 1-1/2 gal of water evaporation a day when you do these things but your water temperature should no longer shoot up when the lights are on.

What is your normal operating temperature and how high are the bulbs pushing this up?

 

[runway1]

Great advice, thank a million!

My normal temp is about 77°. I mounted the new MH lights in a homemade hood that resulted in about 3"-4" clearance to the water surface - hence the acrylic covers.

Seems I'm way too close to the water. I'll modify/rebuild my hood to allow a 8"-10" clearance to the water, remove the acrylic covers and add two 3" fans. From your inputs so far, that should do it. Thanks again.

 

[Thumper]

I have 3 250 watt bulbs along with 440 watts of vho under my canopy. I installed 2 4" Ice Cap fans pulling the heat out by cutting vent holes in the rear of the canopy and installing vented wire screened louvers like go under the eve of a house on the rear. My temp my raise up 1 degree by the end of the day but my lights are a good 7-8 inches off the water.

 

[captivereefs]

coralvue makes another great affordable fan.. I would remove the covers and raise the light sup if you can.