MH HQI Cooling Question

deeze

deeze

Member
Hey, I have an 18" x 60" hood with two 12" Metal Halide lamps that I'm trying to keep cool. I've installed two 80mm computer fans on one side and I'm wondering if they should both be blowing out or one blowing in and the other sucking air out? Not sure what the best configuration is. Thanks a million,
 
dogstar

dogstar

Active Member
If the hood is an open back or you have enough vents then IMO its best to have them both blow out to get the heat out asap, but if theres no vents then one should blow in and the other out.
 
dmjordan

dmjordan

Active Member
Add 2 more fans on the other side of hood. Both fans on one side should be blowing in and the 2 fans on the other side should be blowing out.
 
deeze

deeze

Member
You're right about having another set of fans on the other side but for astetic reasons I can't really do that. It would be to visible. The first set of fans are toward the back of the hood (on the side). Maybe I'll put two more on the front (side).
 
bang guy

bang guy

Moderator
Don't try to cool the bulbs and there's no need to try to remove the hot air in the canopy.
1 - Cooling HID bulbs makes them less efficient.
2 - The hot air inside the canopy doesn't add very much heat to the water.
3 - If you're trying to cool the water then cool the water.... aim both fans so they blow air across the water surface. This will cool the water.
4 - Even if you cool the bulbs that will not cool the water, it will just make the bulbs produce less light.
 
deeze

deeze

Member
Hey Bang Guy, I've heard things like that a lot over the years and I definitely agree with you. I read an article about how the light penetrating the water is what makes things hot, not the air trapped in the hood. That's why I only put two small computer fans in the back corner... just go escape the excessive heat they create inside when I put my hands in to feed and do maintenance. I have them both blowing out.
Interesting point you made about them being less efficient when you try to cool the fixtures themselves... the guys at innovativelights told me the same thing. "Don't blow air on them".
 
bang guy

bang guy

Moderator
If the water temp is fine then don't change anything. If you want to lower the water temp point one or both of the fans in toward the water to encourage evaporation.
The fans also live longer pointed in.
 
jmrents

jmrents

Member
I definately agree with blowing the fans accross the water.
I have dumped my canopy because it gets too hot here to keep one w/o
a chiller and I have upgraded to MH's.
But, I did place an electric 6" fan on my sump and that really helps with the
temp as well, when the lights are on so is my fan, seems to help quite a bit.
Of course w/o the canopy, my tank has cooled down over 4 degrees during the
day, so I am happy 'bout that.
Good luck.
 
deeze

deeze

Member
Yea, you’re right about the fan. I am a great fan of using fans (ok, that was dumb).
I like using fans because it gives me a free water change. I have an auto top off unit that fills the loss.
I found a fantastic little fan at wal-mart that is 12" in diameter and runs super quiet. I have a bigger one in my garage and I call it the Hurricane Fan. I screwed it directly over the refugium about 6 inches above the waterline. The only thing that worries me is the fan motor is a little exposed for motor cooling and the coils are wrapped with copper. Do you think any of that copper will shed off in my system? Only the magnets are exposed to friction but when I see copper I get worried!
Unfortunately the fan doesn't cool enough to keep me at 77 or 78 degrees
 
deeze

deeze

Member
I gotcha. I bought another one because they're so cheap. That way it's easy to replace.
My other tank has 3 80mm computer fans rigged on some pvc dowels. Works great but it's only 70 gallon with a T5 Tec-light (florescent bulbs).
 
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