Fan placement, blow in or out

[jgagel]

When placing fans on your tank to reduce the heating from lights, should you place the fans in (air flow over the top of the tank), one in and one out (one to suck air in and one to blow hot air out), out (suck hot air out)? I know there are probably hundreds of ways to place fans, basically I was wondering if you should have the fans blow toward the water or away from the water?

 

[rwillden]

I use 2- large diameter 12 volt computer fans. One blowing cool air in, and one pulling warm air out. Works great, and my tank temperature never fluctuates.

 

[Reefguide]

If your going to use 2 fans I definately think that one should blow air in skiming the water surface and another blowing out the hot air...

 

[lilko]

here is my experience. 2 fans blowing in works much better for me. i first started with one fan in and one fan out. my tank temperature was still high. i change the orientation of the fans so both blows in and now i can take temperature down where i need it easily. IMO, your hood has to be quite sealed for output fan to work properly.

 

[newkie]

Both should blow in if its an open back and/or the air has someplace to escape. The reason being that the fans will last much longer and perform better.

 

[Reefguide]

Yeah, that does makes more sense to have 2 blowing in is air can be flushed out the back. I have an open back canope but I drapped a thick black cloth over the opening and sealed it. My tank is in front of a window, and at night it looks like I'm growing Hydroponics, or am running some type of mad scientist lab !! 8O Neighbors kept asking me, "What is that bright blue-ish light?" I would first tell them that they would find out soon enough, but I'd give in to them after seeing the looks on their faces Not sure some of them buy the Aquarium theory... !!

 

[jgagel]

Well, my tank is open top, with MH Reef Optix pendants that are hanging. So I will probably place a fan on each end of the tank blowing in at each other.

 

[lilko]

oh, well. your situation is quite easy jgagel. just get 2 biggest (whatever you can esthetically handle) clip on fans from walmart, put one on each side and off you go. You may also use just one fan, nice looking floor/office model.

 

[johns120]

I have one in and one out with open canopy. The disadvantage with fan in, is that you are pulling dust and dirt from the room into the tank-even though most of the tank is covered by an acrylic sheet, this cant be good, so well why havent i fixed it-im just too busy working all the time i dont have enough time for my 120-even now im at work