fans for canopy

[kpatrick]

I recently setup my MH lighting under my canopy and I need to get the water temp down. The canopy is 6ft long (125gallon tank) and roughly 12" high. How many fans would I need to help keep the water temp around 80 degrees? The lighting is (3) 250W bulbs and I am using eggcrate on top of the tank.
I looked on a few sites and they are wanting around $35.00 or more for a single fan kit. Are there cheaper fans out there that come with the wall adaptor or do people wire their own setups? I hate to pay that much then find out I could have saved money by looking somewhere else or buying the parts fan and adaptor seperately and wiring it myself.

 

[bigdjp]

You could get 110v fans from Radio Shack and then just wire them to a plug. I used an old computer power cord for mine. Just make sure you check the db rating on them. I got my fans from my work and they sound like a jet taking off when they start up. After a while you don't notice them.

 

[msd2]

the ones from rad shack are quiet (38db) I cannot even tell when they are on in my canopy. I would say start with 4 and go from there.

 

[kpatrick]

Do you have all 4 fans connected to one power supply?
Also, do you have the fans blowing into the canopy or out of the canopy?

 

[caryn_ia]

All you have to do is hard wire them. I did it a little differently for my nano tho, and hard wired them to a changeable power supply, since the fans are so small (2 1/2 computer fans). I have one blowing in, and the other blowing out. So with yours, 2 in 2 out.

 

[masterzeus]

Another option is to get computer fans prewired with AC adapter from your favorite auction site. I got four fans for about $10 each (plus shipping). They are very quiet and work great. Now the tank's temperature is always whatever I set the heater at.

 

[kpatrick]

MasterZues,
Do you know what the cfm on your fans is?
I just went to an electronics store down the street and picked up a couple 4.72" fans that are 110 cfm each. They had 4" fans but they only had 35 cfm (and only $0.50 cheaper) so I went with the big guys and hopefully 2 of them will do the trick and not be too loud.

 

[masterzeus]

I don't know the cfm is. I didn't see it written on the box. I assume it is pretty low, but they work great at dissipating the heat from the lights. I used 4 on my 55 gallon hood. 2 on each side. One side is blowing in, the other side is sucking out. I think this works well and creates a nice flow accross the lights.
One word of caution: The bigger the fan, the more expensive the hole saw to cut the hole. Assuming you need to cut holes for the fans, they are quite expensive. A 2.5" hole saw can be bought from Loews for about $6, but the cheapest 3" one is almost $20. I don't want to know how much the 4" ones run. I was contemplating using a rotary tool with a side-cutting/router type bit, but it would never be prefectly circular (sp?) and I am kind of a perfectionist.

 

[kpatrick]

Luckily I dont need to cut any holes since I will be mounting these 2 fans on the back of the canopy since there is a large opening across the back. I am going to have them blowing in to the hood and if they keep it cool enough then I will not worry about adding more but if it doesnt work I will get 2 more and blow them outward.
Anyone ever has issues with too much flow causing the MH bulbs to crack? I know not to aim them directly at the bulbs.

 

[masterzeus]

I don't currently have MH, but I saw this question asked by someone else and answered by a lighting expert (don't remember who, but I think it was hellolights). The answer was that it would have to be exceptionally cold air to make a MH crack. Normal air should be fine. But if you are afraid, I don't think there will be too much difference of an effect to have them pointed at the air below the MH.

 

[msd2]

Originally posted by kpatrick
Luckily I dont need to cut any holes since I will be mounting these 2 fans on the back of the canopy since there is a large opening across the back. I am going to have them blowing in to the hood and if they keep it cool enough then I will not worry about adding more but if it doesnt work I will get 2 more and blow them outward.
Anyone ever has issues with too much flow causing the MH bulbs to crack? I know not to aim them directly at the bulbs.
never heard of that, since I would suggest having ur fans turn on before the mh fire up. I have mine on timers to turn on .5hrs before and .5hrs after they shut off. Mine are also mounted in the rear of the canopy pulling air in. I don't know what your light config is but the two 4' fans do an okay job with dual 250wt. When my 17wt hm fires up it also turns on a 3' fan turns on to pull air from the front section toward the back. if your running 400wt mh Id highly suggest putting in more to avoid overheating of ur tank and setup.