MH Cooling fans

[UH_OH_5_OH]

okay here's the skinny..........I got my MH set up and they work fine and look great HOWEVER.....my tank temp soared to 86' F and I may have poached my Sailfin tang had I not unplugged the suckers and thrown a few gallon ziplocks with ice into the sump to slowly drop the temp....several hours later....7 hrs...a comfortable 78'F !


I got a couple of CPU fans from a computer guy at work. I told him what I needed them for and he said to get a "Adjustable Power Charger" rated @/about 1 AMP...hook in a switch...and wire the fans into the charger. There are (3) 4 inch fans and (1)3 inch fan.

Depending on how I position them (one fan blowing toward the bulb and another taking up the air and blowing it out of the canopy)....does anyone/everyone think this will be sufficient ?!?

 

[AZDesertRat]

Have all fans blowing in to the canopy. That way you get the CFM of all four. If one or two are blowing out you just get the CFM volume of two as they is just moving the same air already moved by the other two so they don't really contribute, plus they will get salt build up real quick and quit. I think they work best with one 4" in each end blowing in and with 4" holes in the top or very high up in the back of the canopy. If you use the other fans you may add them down low in back or better yet mount them in your stand blowing across the sump.

 

[phishlet]

Yes, definitely have the fans blowing in make sure you have enough areas for the hot air to be pushed out of the canopy. Open backs work great.

Icecap makes a great canopy cooling 4" fan with a high CFM. I use some from Radio Shack but the Icecap ones are a lot nicer... and a lot more expensive... but probably worth it.

 

[UH_OH_5_OH]

OKAY.....here's my next question then...if the back of the canopy is open....how do I keep that ridiculous amount of MH reflection from covering the wall...?

 

[AZDesertRat]

My canopy is completely enclosed for just that reason. I used the same 4" holesaw I used for the 120mm fans and drilled holes in the top directly over the MH reflectors so heat rises by convection as well as being forced out by the fans but light doesn't hit the ceiling. My two fans are cut back to between 7 and 9 volts most of the time to control speed and noise and it works perfect.

 

[Mike.B]

Ive always heard you move more air if your pushing it out, not blowing in, maybe a few more people will chime in

 

[gvibes]

<a href=showthread.php?s=&postid=7410101#post7410101 target=_blank>Originally posted</a> by subzero420
Ive always heard you move more air if your pushing it out, not blowing in, maybe a few more people will chime in

That may be the case (though I doubt it is significant). However, that would result in replacing the fans constantly due to gunk/corrosion forming on the fan due to evacuating semi-salty water.

 

[Mike.B]

<a href=showthread.php?s=&postid=7410460#post7410460 target=_blank>Originally posted</a> by gvibes
That may be the case (though I doubt it is significant). However, that would result in replacing the fans constantly due to gunk/corrosion forming on the fan due to evacuating semi-salty water.

Last time I checked salt doesnt evaporate and my tank will have a glass lid, the main reason I need the fans. However you might be right for people who do not have a glass top and the humidity inside the hood might eat up fans. So my question still stands push or pull the air out, which is more effective?

 

[ROB2005]

the push- pull method works cause you are basically doing a replacement cycle...cooler air in....wamer air pushed out

 

[Mike.B]

Should I have 1 fan blowing in and 1 blowing out or both out?

note: 1 fan has to blow out because it cannot be mounted to blow in

 

[Blown 346]

I have one of myfans blowing in the canopy and the other pulling air out. My halide canopy stays really cool and My temp is a constant 80 degrees with the lights on and off.

 

[buffer]

i have the same exact problem. i got my MH lights, and my tank temp went to 90 deg. i added 4 lights (2 blowing air in, and 2 on top of my canopy sucking the air out). HOWEVER... this really didnt do much at all. maybe a deg lower. i even got to the point where i had to constantly keep adding bags of ice to the water. lol, as u know... a huge pain in the ***. anyways... i basically had to break down and get a chiller. that was really the only thing that brought the heat of the tank down sufficently. oh... fans are still running. no salt creep to slow them down.

 

[AZDesertRat]

Both fans should be blowing in for best results. If one is in and one is out you just wasted a fan as you only have the CFM equivalent of one fan. You can stack 10 in a row but they would still equal one fan as they just move along what the one before it has already moved.
Have both blowing in, one on each end so they blow across the length of the water surface and have holes either high up in the back or better yet on the top so you also take advantage of convection as well as the fans. Another problem with fans blowing out is they pick up moist salt air and corrode and fail much quicker.

 

[powdertang05]

i would say just go to a FRY's or radio shack and get a converter for like around 10 bucks i use server fans called silver stone they are white quite and move alot of air and also have a controlling nob to change the RPM's up or down and they are around 20 bucks each awesome product my tanks always nice and cool

 

[UH_OH_5_OH]

OKAY.....here's what I did......I used a 5 inch CPU fan on the right side of the canopy blowing in (right to left).....in the middle of the canopy I have a 3 inch CPU fan (also blowing right to left) and on the left side of the canopy another 3 inch fan blowing out. I wired all three fans to a 1 amp alternative power charger.... plugged that into a timer and it is set up to kick on with the lights and kick off 30 minutes AFTER the lights go off. After being set up for 3 days....my tank water was only raised 2 degrees (to 79 F) when the lights have been on all day.

Thanks so much for all of your input folks and I'm glad to see my question generated so much good discussion !

 

[jmaneyapanda]

Here's where I think the confusion is. If the canopy has one of the five potential planes open (ie- the back vertical plane), the fans pulling air out of the canopy will only work if the fans are placed through one of the faces which is closed (which entails drilling a suitable hole in the canopy and mounting the fans). This works fine, and maybe more importantly, keeps the fans from blowing god knows what into the canopy, bulb, water, etc. There is a LOT of airborne contaminants in the air we breathe! It is best to mount the fans opposite the open plane (which unfortunately usually is the face on the front of the tank). I did not want to go this route, so I instead made a bracket, and placed the fans on the open plane itself, with the air blowing in towards the tank. This left the four other planes (vertical front, left, right, and top horizontal) untouched. Im sure I get a lot of debris into my tank though.
The important thins is to force the fan to exchange fresh cool air for heated air. If the fan is pulling air from right next to open area, it will likely not be pulling out hot air, but a mixture of hot and cold.

 

[thaiman]

I have the fans mounted on the sides blowing in with and open back. They blow the heat out the back and also cause evaporation which aids in cooing. I also have to fans on the top pulling air out, that is, pushing towards the ceiling. It seems to work well as my chiller rarely has to work.

jmaneyapanda's opinion is one I agree with and what I did before drilling holes in the sides and top.

 

[UFreefer]

what do you do if your canopy isnt open in the back

 

[AZDesertRat]

Mine is closed in back. I used the same 4" holesaw I used for the fans in the ends and drilled holes in the top directly over the reflectors. That way heat is not only pushed out by the fans but convection plays a part too. Also by being over the reflectors light doesn't hit the ceiling.

 

[cateyes]

bump -- just in case someone else has something to add.... i'm still figuring on mine....