Cooling a Canopy

[cocojakes]

Okay, so I just recently moved up in the world, upgrading to my new 75 gallon peninsula after moving into my new apartment. I built a custom stand and canopy for it, and it looks really great. My only issue is theres no AC here in the summer, and now that its becoming winter, the building heating is a monster. Its warmer in here than it was in the summer sometimes. My tank was overheating, and so as a first attempt I drilled two 4 inch holes in the top of the hood. This helped, but it still hasn't been enough, as my tank still gets to the point where my apex turns off the lights, and I have to go take the sides off the hood to let it air out.

 

I really want to avoid a chiller, so my next step would be fans. All this is really to ask what the best method of installing fans is. The three methods I've come across would be:

 

blowing strait down into the sump (fans barely off the water in the return chamber for example)

blowing strait across the surface of the water under the lights trying to increase evaporation

blowing into the canopy from the vent holes in the top (blowing new air into the hood)

 

what are peoples experience, and preferences here. I think a clip on fan blowing across the surface of the water would be the easiest to implement, but is that really the most efficient way to do it? Or should I be mounting fans in the hood to increase air circulation between the hood and the rest of the room (it does seem to get warmer in the hood than the rest of the room, even with the vents)

[AZDesertRat]

I have done several write ups on my experiences with fans but can't lay my hands on one at the moment, a search with my username on most of the reef forums should bring some up.

What I came up with as the most efficient for me is two 120mm computer fans, one in each end and both blowing in along the longest water surface with equal size or large holes in the roof of the canopy for hot air to escape. I found even when the fans are not running you can feel heat rising out the top by natural convection alone. My fans are 13 years old and they are probably better ones now but they are Vantec Stealths and are still extremely quiet to this day. I power them with variable voltage DC power supplies (wall warts) so I can vary the fan speed with the seasons for best cooling without excessive evaporation or noise. They can go anywhere between 6v and 12v but normally run at 7.5 to 9 volts so slower and quieter still. When I had metal halide and VHO fluorescents the fans started on a timer about the same time as the lights came on and went off about an hour later depending on the season and cooling needs.

 

I tried AC powered fans (too loud and no variable speed), faster and samller fans (again too loud due to the high speed), one blowing in and one out which loses the capacity of one fan since the second only moves what the first feeds it, on top blowing down which fought against convection, both on top sucking out but they gummed up and quit due to the moist air and dust, both in back but they didn't blow acress as much surface area etc. I tried them all, even variable speed fans with an internal temp sensor but they never slowed down.

 

If you can find some of my write ups a few even had pictures. The best one I did was for my local reef clubs home page but they went under and I didn't save all my articles ahead of time so lost them all including some good ones on RO/DI, energy conservation and DIY tank stand and canopies.

[Bingo1213]

I use a 6 inche diameter fan pointed at the water surface in my return section. Works great! No issues what so ever!

[braaap]

Pull the canopy off. Throw canopy in trash. Canopy is now cool.

[Hig789]

Back when I ran VHO and metal halides on my 90 I had two 4" computer fans, one blowing in and one blowing out. It did a excellent job of cooling it but if it did get too hot I would just prop the front door of the canopy open a little ways to let more air in/out. Or like said above you could just get a clip style desk fan and have it blowing across the sump. Im sure either would be sufficient but I'd leave the holes in the top of the hood open to help with rising heat.

[Bingo1213]

Don't throw the canopy. Imo it is annoying to look into a tank that doesn't have one since the lights shine in your eyes. Mine has one and a fan in the sump is all I need to cool it.

[Hig789]

Don't throw the canopy. Imo it is annoying to look into a tank that doesn't have one since the lights shine in your eyes. Mine has one and a fan in the sump is all I need to cool it.

 

I agree with this. Unless the lights sit right on top of the tank the light spill is annoying. I think canopies make tanks look good, like a moving picture without having to see the lights and stuff hanging over the tank. There are many good looking rimless tanks with no canopy but it's just not my thing. Also helps to keep toys, other people's hands and other stuff out of the tank.

[cocojakes]

so here's what I did.

 

There were already 2x 3.5" holes drilled in the hood (its a 75gal peninsula tank, so 48" long, the short end against the wall) one 6" from the front, the first kessil hangs 12" from the front, the next hole is 30" from the front, and the second kessil 36" from the front.

 

What I did, was I drilled a 3rd hole, right at the back, above the overflow (about 48" from the front) and placed an 8" clip on fan right above the overflow, pointing down across the water. It now turns on when the tank gets too hot, and drops the temp dramatically. You can see on my apex, the temp rising (it took only 4h for it to rise 0.5F) and then as soon as the fan got plugged in, it dropped like a stone, that same 0.5F in just under an hour.

 

I might have to do some complex coding in the apex to make it not cool the tank so fast, but it for sure works. even in the oddly shaped, oddly constricted canopy. Just so anyone following knows, the problem was solved quite readily by a fan.

[Bingo1213]

I have my fans programmed as one would a chiller in my apex. The coding isn't too hard. Something like...

 

Fallback OFF

If Temp > 80.5 Then ON

If Temp < 78.5 Then OFF

[ManGups]

I use a jbl c-breeze and have it controlled via an apex. I set it up such that it run only to drop only 1 F so it does not cool that tank too much.

 

On. Hot day it turns on multiple time and keep the temp wit jining the 1F variance.

 

You can also program using apex that it runs on and off so that it cools slowly. On the other hand if u want the fan speed to vary temp deviation from the control temp .. I think it may not be possible via an apex since you DC control and control the amp of an outlet.

 

I would intrested if any of u have ideas.

[Bingo1213]

Right you can't speed up or slow down a fan with an apex directly. The VDM ports are not designed to power equipment but to send power to a dimming module such as a 10V dim able ballast. Directly powering a fan off this port could cause damage and or not work properly. Now if you could find some sort of "ballast" or module to receive the 10V current from the apex and then translate that to the fan I'm sure you could throw together a code. Even if it just ran the fan speed by the time of day i.e. in the morning it can run slower and then ramp it up when the lights are at full intensity and then ramp it back down at night. You would want some type of a temp code in there telling the apex to turn the fan completely off if the temp gets too low or you'll just be fighting with your heater. But other than that it could be completely time based.