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To Boldly Reef ...
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Here's an update. I bought two 4" 80 cfm fans and installed one on each side of my stand located in the upper back portion of the sides. Both are installed to blow air out of the stand, with two new 4" vents holes cut into the bottom portions of the back wall of the stand. Hot air gets vented out the fans near the top of the stand, and cool air gets sucked in via the two new 4" vent holes at the bottom of the back wall of the standand and the previous 2 1/2" vent holes in the middle portion of the back wall of the stand.

Keep your fingers crossed.
 

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It's looking GOOD :drool: . So far tank temps have not topped 77.6 degrees. I have been running the tank with the lights off for the past two days since I installed the new 80 CFM fans in my stand. Before, the tank was setting at 80 degrees with the lights off. Now, for the past two days, it has been setting at 77.4 degrees with the lights off.

Next step, turn the lights on and see what she does. So far, So good.
 

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Why I get nothing done...
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I have all my fans blowing air into the hood and stand. I personally think this works better because instead of sucking all the doors shut it will actually keep them slightly cracked for air to escape. Also my fans in the hood are blowing down onto the water and do a really good job of evaporative cooling. I'm using some computer fans, Antec, that are way cheaper than aquarium fans and are super quiet, high CFM. I also think that by blowing, you don't suck humid air through the fans causing them to fail/rust so quickly even though my fans are plastic and won't rust.
One other thing, my tank is located next to an AC vent, so by having the fans blow into my stand it sucks very cool air from the AC directly into the stand. Sometimes when I open the stand it's almost cold in there.
 

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Thanks for the input tashier. In thinking about venting the stand, something occurred to me, and was actually mentioned by someone else eairler in this thread, about the fact you typically don't see vent fans setup to blow cool air into a closed space as much as you see fans vented to PULL hot air out of a closed space.

Think of fans cooling computers, the vent fan in your bathroom, attic vent fans, etc. They typically are setup to blow out, not in (at least this is the way my house is wired unless the contractor screwed up:p ). As far as hot humid air rusting the fan, wouldn't this happen to your bathroom fan over time when you use it to vent the bathroom after you take, or while you are taking a steaming shower?

To give you the full specs on how I have my stand vented, like I said I have installed two 4" 80 cfm fans to blow out of the stand. Right now I only have one on full time. The other is controlled by my Aquacontroller Jr, to be turned on in the event the temp probe records a temp above 82 degrees in my display tank. Otherwise it is off, and I am taking use of physics (specifically the negative pressure or vaccum generated by the one exhaust fan) to pull cool air from the outside through the second fan that is not running AND through the two new 4" vent holes that I cut in the back of the stand. My tank is also located near a AC vent. It blows down the back of the tank and thus the "warm air rises, cool air sinks rule" is used as the vent holes are in the bottom portion of the back stand wall, to take advantage of cool air near the floor. The fans, being at the top of my stand, vent the hot air "rises" part of the picture out the top of the stand.

Right now the stand is pretty cool, and definitly not humid anymore.
 

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Why I get nothing done...
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Yes, I understand the PC fan theory, which is only partially true. Usually they blow out but not always. A lot of CPU fans pull air in from the outside because the air outside the box is a lot cooler. I think it depends on your application. Since my fans blow in, they blow right down onto the water which will cool better than any fan sucking out. Also if my stand fan were blowing out, it wouldn't be drawing in cold AC air. Just depends on your application but I don't think saying sucking air out is always better. My temp dropped when I installed my fans from 87 to 78 in one day. I did eventually get a chiller for backup and it runs a few times a day.
 

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Well, I'm not sure that I agree that fans blowing in always cool better. The whole point of using a fan for cooling is to tak advantage of evaporative cooling. Evaporative cooling slows down if the air over a body of water, in this case our tanks, is saturated with water vapor already. The point of the fan is to physically move the heavier water vapor laden air "humid air" out of the way and replace it with dryer air "which is usually cooler" so it can suck up more of the warm water vapor and then move out of the way to allow more dryer air in its place.

Now if you're using the fan blowing in to disturb the water surface which will aid evaporation that will speed cooling. If you are using a pump, water return, wavemaker, etc to break the water surface to create turbulant flow this will aid in cooling as well.

In my case, I have four fans in my hood. Two blowing in and two blowing out with the back of the canopy completely open to take advantage of the cool air from the ceiling AC vent. I have two Tunze streams breaking the tank surface water to aid in cooling/gas exchange. The two fans blowing in, augment the two blowing out for better air flow over the tank and faster evaporative cooling.
 

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Electrical G "EE" k
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drdude,
I think your setup will work great. I would agree that having all the fans blow into the hood would not be a good idea. However, only using fans to suck air out is not maximizing the cooling abilities through evaporative cooling. I think your setup is great. On my MH setup, I have four 60mm fans that are setup on the back edge of the tank blowing over the water and out the front. Since I use no hood, i don't need to suck any air. I just aim the fans slightly down at the water. I have no chiller or AC in the house and this summer for about three days the temp was 100+ and the tank never got above 85.

One other thing to think about...I have heard arguments that you do not want to blow fans directly on MH bulbs. This may affect the burning temperature and likewise affect the PAR of the light. I feel this applies to double ended much more than single ended, since single ended are already encased in the glass bulb itself. Just my two Pennies.
Jeff
 

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I guess the point of differing view is the fact my fan is blowing out of my stand? Maybe I should clairify that the purpose of my fan in the stand is to vent. If you do the math for my stand which is 6' x 2' x 4' that is 48 cubic feet. Since I am using an 80 CFM fan that is 16 cfm shy of turning over 2x the volume of air in my stand per minute, which is replaced just as quickly by cool air moving into the stand to replace the air blown out. If I kicked both fans on I would be venting about 3.75 times the volume of my stand per minute.

I'm not saying my way is the best way, or the only way. And I deffinitely don't want to come across like I am arguing. Trust me, If this doesn't work well enough to cool the tank with the MH's on, I will be right back here at the drawing board trying to come up with a better mouse trap.
 

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Yeah, I hear that. I wuld like to get one at some point, but the budget is already screaming in pain from most of the other equipment I have bought. If I need one, then I will get one, as in the long run my tank will thank me for it. But I am really hoping I can get along with out it.
 

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Electrical G "EE" k
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Chillers are very nice, but I prefer the fan cooling. As long as the fans can keep it cool, why spend all the extra money on a chiller? You will probably need a temperature controller of some sort to get the accuracy of a chiller, but you will still save money in the long run.

Also, don't forget that fans have one big advantage over chillers...evaporation. This allows you to add Kalk must faster than on a system with just a chiller.

Not trying to argue at all...just bringing up both sides of the story.
 

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I use a 14" fan under the tank that sucks from the back outer opening to over the wetdry and back up under the tank glass. Went from 80-82 to 78 on a hot hot day.
 

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r6413utah said:
I use a 14" fan under the tank that sucks from the back outer opening to over the wetdry and back up under the tank glass. Went from 80-82 to 78 on a hot hot day.
no kidding how did you mount it?


Got any pics?
 

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Well, after three days of observation, and running my MH and VHO for about 6 hours each day. My tank temp has peaked at ..... 79.5 degrees! Yes .. Yes ... Yes ... cooling problem ........... solved.
 
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