Cool off your tank, cheaply!

There are a variety of ways to cool a tank. Many people use fans available at Home Depot or Walmart, because it doesn't cost much and can bring the temperature of the water down several degrees. This is very important with the summer months approaching.

I have a small Hamilton 3" fan blowing down on the surface of the water in the return section of my small sump. When I designed it, I wanted to make sure the fan was secure and wouldn't fall into the water accidentally. I also wanted to be able to easily remove the fan so I could clean the acrylic framework.

Click for larger close up image

This idea was well-received in my club, and also featured once before in an article published on Reef Central. Recently a club member approached me and requested I make him a tray to hold two 4" IceCap fans, so I got to work. :)

The first thing was to find out the span of the area the unit would set into. In the case of this sump, the area was 11 7/8" wide. The measurement to the outer edge of the sump from front to back was 12 3/4". If you look closely at the image above, you can see how I cut notches so that the frame could rest on the plastic trim of the sump. The base fits inside that trim, hanging down merely a 1/4".

To create the openings, I created a wooden template. Once that was done, I clamped my acrylic piece on to the template, and drilled a hole inside the zone that would make that octogon shape. Cutting it out was easy with a Laminate Trimming router bit, as the roller bearing guided the blade as it traced the template's edge.

I wanted to make sure the fans would fit nicely and securely, so they wouldn't vibrate to travel. Mounting small rails in the center keeps them in place, and doesn't interfere with the wiring. IceCap fans come in two sizes - 80mm or 120mm (3" or 4"), and include a temperature probe. As the ambient air temperature increases (within your canopy), the fans increase in speed. When the temperature drops, the fans slow back down again. They run very quietly at three different speeds, depending on the temperature. The fans are 12v, and each one comes with its own transformer plug (some call those "Wall Worts" because of their ugly size). IceCap is proud of their fans, which run about $40 each, but you are getting a fan that is designed for saltwater exposure and to run as silent as possible.

Done. :)

When I gave it to him at the meeting, he was excited. So the rest of the comments and pictures are from him...

Marc built it in no time from just a couple of measurements that I provided him, the overall width, and the width inside the plastic rim of the 40H glass aquarium that I use for a fuge and sump. I gave him the fans and those 2 measurements and it fits like a glove!

I run a chiller so I can't give an exact temperature drop but instead of it coming on many times per 24 hr period (including at least twice in the middle of the night!), the chiller runs maybe 3 times in the hottest part of the day with lights on. My controller is set at 80 right now but I may bump it up to 81 or 82 in hopes of doing away with the chiller altogether.

I'm able to triple my kalk drip and am seeing an ~.15 pH average increase and my alkalinity is holding steady.

Overall I can't believe how cool it turned out! Whisper quiet, precise fit, and all the [benefits] from increased cooling and evaporation.


Strategically placed temperature probes for maximum rpm (still quieter than my pumps).

Not much room! A clip on fan just didn't work under here.


I can slide it from side to side if needed.

To learn more about ways to cool your system, please read:
Beat The Heat: Aquarium Cooling Methods by Kevin Kocot

Email Marc