4" Fans... too big?

[esalve]

I have two 4" fans hooked up on my canopy - one blowing in and the other blowing out. The canopy is 84"X24"X13" and I paneled off the back of the canopy to ensure a smooth consistent flow of air past the lights. There are currently two 250 w MH and I will be adding some flourescents which are not hooked up yet. So here's what I am experiencing: the fans never speed up and everything appears to be cooling very nicely; however, the fans are all I hear now. I'm thinking that I simply oversized the fans and should have gone with the 3" ones. The specs on the IceCap website show a significant difference in CFM between the two sizes - do I dare down size to the 3" ones to reduce the sound or will I then have cooling problems?

[ASH]

Are the fans on the inside of your hood? They should be.
I'd have both blowing inward and verify they're running at slow speed. At their slowest speed they're near silent.

The 3" would be louder so don't go there. How they're mounted might be the real issue here. Call 800-742-3227 ext. 22 for some hints on quieting things down.

Andy

[esalve]

Andy -
I do have the fans mounted on the inside of the canopy but they are smack against the back. I mounted them snug with two machine bolts. To test the variable speed of the fans I took the temp sensors and put them on the outside and held them in my hand to speed up and slow down the fans, all seemed good there. Here are two pictures of the hood - left fan blows in and right fan blows out (haven't had a chance to reverse the right fan as you suggested). If you can provide some suggestions based on what you see that would be great, otherwise I'll give the phone number you posted a call and go from there.

THANKS!

btw - IceCaps customer support is one of the main reasons I decided to buy IceCap products, just never thought I'd be making use of it on something like this - keep up the excellent work!!http://reefcentral.com/gallery/data/1/76904canopy_left_2-med.jpg http://reefcentral.com/gallery/data/1/76904canopy_right_2-med.jpg

[ASH]

I'm guessing this is a new tank. Once you have you pumps and skimmer working the sound of water movement alone is usually louder than our fans (except when they're on full blast).

To see what they really can do, partially dunk the probe into some very hot water (not salt water).

It looks like you have a metal inner skin to your hood which may be resonating with the fan. A felt pad or rubber gasket might be needed. I would call Chris at the number above for some suggestions.

Looking at the hood I've got to ask, are both 250-MH bulbs in the center or on a track? Lastly, if you haven't already made a purchase, consider T-5 HO lamps for your fluorescent lighting.
Thanks for the pictures,
Andy

[esalve]

Thanks Andy,

Yes, this is a new tank setup. I've done several things to keep the sound to an absolute minimum like running two smaller pumps instead of one large one, used all flexible hose to bring the return water to the sump with gentle turns and minimal vertical fall. So far it has worked out well and all I was hearing was the low hum of the pumps. So when I added the fans they really stood out.

Both MH are mounted on center from front to back and spaced evenly from left to right. There is no metal in the canopy, the sheen you see is from the hardboard I used to enclose the back of the canopy (good reflection, water resistant and cheap :) ). Though this stuff is not metal it could be amplifying the sound as it is very hard and smooth. I already bought some IceCap T5 endcaps and standoffs along with a 660 ballast but these are not hooked up yet. Having trouble finding T5 bulbs locally and I'm trying to decide if I should just go with T12s so I don't have to order in T5s.

Thanks Again - in a world of poor customer support you guys are a breath of fresh air!

[ASH]

Try www.ReefGeek.com for T-5 HO lamps.

thanks,
Andy