DIY Cooling fans?

[candian bacon]

My tank temp is starting to get a little high. 80F and climbing with the warmer days ahead. Id like you thoughts on installing 2 fans in my hood?

Im thinking about having 1 fan bring cool air into the tank and the other on the oposite end to take the hot air away?

Id like to have these fans on a therastat if thats posible? Has anyone done this before? what would i need for power and what rating of fans? like 12v?

[Geoff]

here are some ready made thermal fans. they are used for computer thermal control

my theory on tank cooling is have the fans blow out. cool air will come into the hood, it has to. you have created a pressure gradient and the air will have to fill in or the hood will implode.

to help any kind of fans you will also need to keep a good amount of surface agitation to help in the evaporation.

G~

[Phishnoob]

I did one going in and one going out. I understand Geoff's pressure gradient theory but my cover fits really snugly on the tank and I was worried about enough air getting in. There was a plastic cover over the tank but with it removed the temperature dropped a lot. The only drawback with all the evaporative cooling is that top off is almost 2 gallons a day with my 90g and 25g sump.

Phishnoob

[gregt]

The nice thing about having an incoming fan is that you can have it blow on the water surface aiding in evaporation.

[bigjohn]

I vote with Gregt. I have my 2 fans pulling air in. Geoff is exactly right in his "implosion" theory, but I decided to do the opposite and try to create a hood "explosion".

Also I read in another thread that pulling in fresh air (versus pulling out hot air) would reduce salt creep on the fan.

[gregt]

I do recommend at least one fan pushing air out. My tank currently is using a full sized box fan blowing air in. (It's a large hood) Until I added two small fans blowing air out, I continued to have heat buildup in the hood even with this huge fan.

[Geoff]

i have found that when a lot of fans are blowing in the heat just keeps building up in the hood. there seems to be a lot of eddies in the hood that just will not clear out. the heat does not have any real way of getting out. the pressure gradient does work both ways but it is always easier to pressurize something than to creat a vacuum.

haveing a fan blowing on the waters surface is a great way of helping evaporation. now whether or not that fan is a part of the hood/canopies ventilation system is a different story.

G~

[candian bacon]

thanks guys! Some good tips from all.

has any one tried putting these fans on a thermastat? or are they just wired to run constant?

[wanareef]

I have both of our fans "blow in" just for that purpose of salt creep and to help in evaporation. We have a timer on the fans to come on with the MH's.

[hesstondc]

If I just added the fans to my sump would that cool it just as well? I don't want to hear fans blowing all the time in my den...

Thanks

[Phishnoob]

I think the fans should go in the canopy and they are not too loud. The canopy is the place with the heat buildup..also my canopy is a sealed box instead of just a frame with thin wood and an open back and probably quieter.

The other big reason is that the cooling is evaporative as much as the fans drawing out air via convection and the surface area of the water has to be a big factor.

Phishnoob

[Rob_Reef_Keeper]

I have 2 3-inch Ice cap fans on my canopy with an open back. Those fans were not cutting it.


I put a 6 inch clip on fan in my canopy blowing across the water and that cooled the tank drastically, I had to actually shut off the fan allot.

I went and got a dual stage controller and the tank is steady a 79 degrees.

[candian bacon]

I have a glass top on my tank as well. I am only runing 4 NO florecents at 30 watts each. I buy my ro water so i dont want to much evap. thats why i have the glass top. PLus my tank is in the wall so it cuts the salt crep down and keeps my wall from rotting out.

Maybe i will just cover the front of the tank the in wall side?

im going to post a few pics of the tank set up

[candian bacon]

this is the cabinet that i built to hide the back of the tank.

[Taxman]

Kinda late here but I just set my fans up.

My thermomter went on the blink and I had been running my water temp at 84 night and up to 89 at the end of the light cycle. I was wondering what was happening to my corals.

I installed 2 fans yesterday from a local HVAC supplier that blow 110 cfm each. I placed one in each rear corner of the hood and they come on with the 1st MH. today is the 1st day of the fans and this droped the tank to 86 at the end of the light cycle. They do blow onto the water surface as well.

Then today I added one in the stand. I installed a small oscillating fan from home depot that has a T-Stat on it already. It has a mount on the bottom that allows you to mount it on a wall. Very nice. And only $20.00 ... I set it to 80 deg air temp for it to come on. It is blowing about 50% into my Fuge and the rest just blows through the stand. My current temp is now 80. The lowest temp without the fans has been 84 first thing in the morning. My equipment alone was keeping it heated up. So the fan under the tank helped me the most.

I will post tomorrow on the end of lighting cycle temp with all fans running. Hopedfully 84 or less.