How Many Fans in my hood?

freeflyer · 03-31-2004, 08:48 AM

I am going to buy some ICEcap fans for my hood today and I was wondering how many I will need. These are the ice caps that have a temp sensor on them and can change speeds depending on the heat. I have a 125 gallon tank (72x20x20 i think) and I have 3x250w 10,000k MH and 4x55w Atinic. I was thinking of 3 fans, one for each MH, but is this overkill? Thanks for the input!

Mike

crab0000 · 03-31-2004, 11:10 AM

I think two will be fine, one in each end, if the back of the hood is open.
Steve

Geoff · 03-31-2004, 11:11 AM

as many as you can afford.

a lot has to do with how tall the hood is. the taller the hood the less fans you can get away with. 3 is prolly a good numbe. these are 4" fans correct? that is a good size, can move a lot of air.

as for positioning the fans, that is a whole another thread.

G~

seamonkey · 03-31-2004, 08:27 PM

It actualy all depends on the cfm's that the fan can move. When I made the fan set up for my hood I figured the lighting watts, the height of the hood and a bunch of other things that would take to much time to explain. basicaly with my lighting set up and every thing else it came out to haveing to move the air at 452 cfm. Air temp and the temp I wanted to maintain in the hood were the main factor and I chose the temp of 76(my house temp year round). I ended up purchasing 4 115cfm 4" axial fans and making a auto temp probe to turn them on an off. I have a 240gallon long tank so I decided to mount the fans in the back of the hood and put vents in the sides and front. So your best bet would be to check the the fan cfm's and see how much air your pushing with them. I would say 2 would be fine but for the safe side go with 3. Make sure you have the same opening size for intake as you to for exhaust on your hood if you want it to work best.

Junkzoo · 03-31-2004, 08:51 PM

One blowing in, Two out,,,IMO
I had my in -blowing one go out, and during the few days i waited,,,temps went sky high!(90degs)
2-400 watt 10K mh's,4 -55w PC actinics , on a 75,,,
replaced the in-blowing, and temps stayed back to 76 degs,,,
never thought i wouda made that much of a difference,,,,,
but my canopy is pretty much enclosed, with very little open , near the HOB skimmer,,,