People who cool their tank with a room AC

[rickh]

Lets hear from people who cool their tank with a room AC. We are always hearing stories about how well it works. My friend tried it unsuccessfully. The AC ran continuously, you could see your breath in the room and the tank was still too hot. R

[Ti]

How cold was the room and how hot was the tank?

[seshapir]

we cool the tank with our AC. We have 3 250w HQI's running and I'm not running the AC super cold. I think I'm having good luck with it because the AC vent is right by the tank. I think it just depends on the tank and where/what kind of AC is running.

[joelsaxton]

I have a 240g tank with 4 250w MH lights and 8 110W VHO's and the AC keeps the tank temp below 83F at all times. The tank temperature rarely drops below 80.

[twon8]

as long as you have adequate ventilation bringing the cool air into where the hot air is it will work fine. a backup to turn off lights if temps hit 85 wouldnt' hurt either.

[hahnmeister]

Using the AC to cool the tank works as long as you enable the tank's ability to transfer the heat. If your room is freezing and the tank is still too hot, that means that the tank is too well insulated. Sounds like you must have a sealed wood canopy, a solid unvented stand, etc. Adding a fan to the setup that blows across the water surface is all most people need to keep their tanks at about 80 degrees, even in room temps that are above 80. The heat transfer due to evaporative cooling is very effective...the phase change from liquid to vapor absorbs and takes with it alot of thermal energy. Its a bit like you are parking the car in a cold garage, with the heat cranked up to heat the garage...yet the windows and doors are closed.

You just need to maximize the heat transfer potential. You also might try an enclosed hood with a power vent that goes outside. Thats what my cousin does on his 180g with 1200 watts of lighting...he used 4" duct with a 100-200cfm fan that sucks the air from in the canopy over the tank out and puts it outside. This greatly decreases the amount of heat that the A/C has to deal with, and it means that cooler indoor air is being drawn across the water surface to keep the tank cool.

[compulou]

My tank was actually pretty close to an AC vent. So what I did to help with cooling was to purchase an AC vent from HD that allows the air to be pointed into any direction. Now when my AC turns on it blows right onto my open top 65.

[joelsaxton]

do these vents fit any standard AC unit?

[RicGio]

You've gotta get good airflow out of your hood and across your sump. The best AC unit in the world won't cool your tank if you have no convection going. Conduction heat transfer can only do so much, and the surface area of a tank is kinda limited.

My 40 long is in a room 8' x 16'. I keep the door shut, got I fan on in my hood, another across my sump. With a 5200 btu window unit running I can keep my tank at 80 F with a room temp of 72 F.
I'm running (4) 110 watt VHO's (no metal halides) which run pretty hot...but not as hot as MH.

[hahnmeister]

Its not that the surface of a tank is limited, its that everything but the top is insulated. Glass is insulation, wood is insulation, plastic is as well. You need to make the most out of the area that isnt insulated...the water surface, and to a varying extent, the overflow drainpipe.

RicGio, I run a 40B in a room w/o A/C sometimes, and all it takes to keep it cool is a fan blowing across the open top (easy to do with a halide pendant that leaves alot of surface area) even with a 250watt halide. I say this because I suspect in your case that your 4x110watt VHOs are producing more heat (or at least transferring more to the tank) than my 250watt halide is. I would strongly suggest you look into halides as a cooler alternative, of course, your tank's length makes T5s a better match...a 4x54wattT5 unit is what I used over a 40L a little while back...the amount of light would most likely be more than your 4x110wattVHOs.

[mg426]

I use a room ac unit. I also have a cooliing fan over the refugium that comes on at 81 degrees. Tank has not been over 81 all summer (so far) I have four pumps submerged and one external.
so far so good. No chiller allthough That would be nice to have.

[RicGio]

Naah...my hood is too shallow for halides. I'm not having a heat issue. Glass is an insulator, just not a very good one. To cool a tank by conduction alone youd need a pretty big difference in temp and a lot of surface area.

[Zoom]

I have three vents in my living room the central AC set at 74F tank temperature never over 80F but i run very efficient system very low watts return pumps , skimmer also three IC ballast for 250W MH and two 96W PC.

[JerseyReef]

I run an open 40 with a window AC unit in a house that is on central air. The room's central air vent is in the closed position during the summer and open during the winter.

The window unit is connected to a two stage controller (which is key to making this work), which is set to come on when the water hits 81. When the water drops down to 80, the window unit will turn off.

The vent from the AC runs across the open top area of the tank.

[vijaym85]

I have a mag18 and a mag9.5 as well as several other submersible pumps plus 1200watts of halide and my tank stays under 80 thanks to keeping the tank about 3ft from a 5000btu ac and 2 8inch cooling fans. The tank is 150gallons and I get about 2 degress of temp flucuation from day w/ halides to night. water has a high specific heat so heating or cooling it requires large amounts of energy. This system works for me and is cheaper then a chiller but certainly would be harder with smaller volumes of water and definately not as consistent as a good heater chiller combo.

[km133688]

AC works only because of evaporative cooling. Water has a pretty high specific heat, in fact it has the highest specific heat of all common substances (how bout that, I sound smart...).

For those of use who were not awake during 7th grade science experiments, specific heat is the amount of energy needed to raise the temperature of one "unit" of mass by one degree celcius. The specific heat of water is 1 calorie/gram (hmm... calorie... gram... that sounds familiar).

Anyway, if we reverse the idea, then to drop heat, water must lose more energy than any other substance you are dealing with. Thus you need some way to help the heat get out of the water, otherwise know to reefers as EVAPORATIVE COOLING.

All done and said, it don't really matter what the temp is of your room if you ain't moving the air across the water. If you expect the cool air to remove heat from your tank, it has to come into contact with the water so that the heat in the water has some place to go (along with some water that will also evaporate).

AC is the easiest way I know of cooling a tank unless you have special circumstances. Lets face it, you can do only so much with evaporative cooling, and maybe your specific lighting and other heat output is so great you need to consider other methods. But for now, I'd check to make sure you are getting the right air flow across your water like everyone else already said.

If you are really stuck, dryer air evaporates more water than humid air (duh) and thus might increase potential for heat transfer, so you can get a de-humidifier and put it in the room too. Course, you are going to have to change your water makup schedule if you increase your evaporation rate.

Good luck man, Kevin.