DIY Quiet Fish tank cooler

[Reivax]

Hello

How do you cool your tank water during summer?
I didn't want to buy a cooling unit which is a bit cumbersome and overkill for my needs, so I started buying fan ramps.

But they are SO noisy!! I can't believe they dare sell this stuff.

So I designed one using Noctua fans, which are high-end computer cooling fans, very reliable and silent. Their air throughput is slightly less than the ones from tank-purposed fans I could find data for, but they work fine.
The Noctua fans are pricey, but I think they are worth it: they are so silent that when I'm standing in front of my tank, the only way I can know if they are running is by looking at them.
Their angle is adjustable using butterfly nuts.

Here are all the information you may need to build one (but drop a message in case you need help)

Printables

www.printables.com

I've made it modular so that you can build it the size you want to fit your needs. You need to 3D print the parts depending on how many fans you'll use, and solder their power cables in parallel.
The first one I built for my tiny tank has only three fans

Then I built two with 5 fans, and two with 7 fans, for my friends bigger tanks.
I added a middle foot to the 7 fan ramps, since it's really long.

 

[Jay Hemdal]

Cool idea! I have used computer fans (singly) for cooling smaller tanks, but never tried a bank of them. Many years ago, for my Advanced Marine Aquarium Techniques book, I ran some tests on fan cooling of aquariums (since chillers are so costly). I found that strong fans had an added benefit of also creating a huge amount of gentle turnover water flow. Here is that text (from 2006):

One solution to this problem, a refrigeration/chiller system, is often prohibitively expensive both in initial cost as well as in operation. When the desired water temperature is less than 5 to 7 degrees Fahrenheit below the ambient room temperature, aquarists have successfully relied on the evaporative cooling effect produced by moving air across the surface of the aquarium with a fan. However, the aquarist must either turn the fan on and off as needed, or set the thermostat on the aquarium’s heater at a higher set point to avoid over-cooling the water (and then accepting the higher energy cost incurred while periodically running the heater and fan simultaneously). It may be common knowledge to some; but by using a standard water chiller thermostat, the fan can be controlled more precisely, often holding the aquarium’s temperature to within one or two degrees of the target temperature.
In one example, when a 1500 gallon reef exhibit was test-filled, it was discovered that the light coming in through the skylights, the additional metal halide lighting and the large number of pumps all contributed to raising the aquarium’s water temperature to 83 degrees, six degrees above the target temperature of 77 degrees. A 20” - 1/6th hp fan with airflow of 7500 CFM, was attached above the tank, directing air horizontally down the length of the aquarium, with the lower edge of the fan about 6” above the surface of the water. This lowered the water temperature to within a scope of 73 to 77 degrees. However, this wide temperature range was not acceptable, and was caused by the variations in the evaporation rate resulting from changing humidity levels and daily fluctuations in the room’s air temperature. By plugging the fan into a Goldline chiller controller (model SP-33) it was possible to reduce this temperature range to one degree, between 76 and 77 degrees. The controller would now operate the fan when the aquarium water warmed up in the heat of the afternoon, and then be turned off in the early evening when the water was cooler.
Two additional benefits became apparent. While the fan was running, substantial water currents were generated and a series of light-refracting wavelets were produced. The flow of the water current was calculated to be 2700 gallons per hour by timing a drift bottle driven down the length of the tank by the current produced by the fan. It should be noted that this was a theoretical maximum, measured with all of the aquarium’s pumps turned off – in normal operation; the affects of some of this wind-driven current would be cancelled out by the opposing currents produced by the various oscillating pumps. In regards to the surface wavelets produced, they were noted to have some affect on the light regime within the aquarium. Using a submersible light meter situated 12” below the water’s surface; a still-water reading of 375 footcandles was taken. With the fan on, the wavelets refracted the light, causing the light level to shift rapidly between 330 and 370 footcandles. The overall effect of these glitter lines (or ripple lines) is esthetically pleasing, and the reduction in average light transmission into the aquarium had no apparent affect on the animals (as this system was already well lit with metal halide lamps). With the meter’s probe held horizontally, the still water reading was 50 footcandles. With the fan on, the level then varied between 50 and 75 footcandles, actually increasing the amount of reflected light traveling horizontally in the aquarium. This may have some minor benefit for getting more light to the base of corals otherwise shaded from light only coming down directly from above.
The only drawbacks to this method seem to be the greater need for make-up water to replace that lost due to increased evaporation, and potentially shortened fan life due to its operation in a salt-laden atmosphere. In some installations, the aerosolization of seawater into the room causes serious corrosion problems for electronics, walls, etc.

Jay

 

[Reivax]

Hi, this sounds interesting.
I don't think the kind of fan I have used have enough power to create current, I have not noticed any but I wouldn know, since one of my underwater flow pump is oriented to move the surface as well, so, maybe.

To control the temperature I'm using a cheap "Ink Bird" regulator (not this exact version though, the sensor is not the same)

You set up a target temp, and it will trigger either heating or cooling to reach it, and it's pretty accurate, here is a picture I just took:

Only 0.1°C difference from current to target temperatures.

But yes, fan cooling increases evaporation. I have a filtered water reserve about 1/3 of tank capacity, and an osmolator to automatically compensate. With that I can safely leave home for 3 weeks in a row.

 

[ナイトコア猫]

Fans with larger diametre are more effective.

 

[Reivax]

Fans with larger diametre are more effective.

Of course. But they would look uglier. Not that they are pretty right now, but they fit the purpose, no need for bigger ones.
Also, bigger ones would lean forward more, and block some of the light.

 

[ナイトコア猫]

Of course. But they would look uglier. Not that they are pretty right now, but they fit the purpose, no need for bigger ones.
Also, bigger ones would lean forward more, and block some of the light.

That's right. I agree. I like small fan's aesthetic.

 

[jda]

Used fans for 25+ years. If you can make small and quiet ones work, then that is great. The next step is turning them on when your lights come on or before it gets hot - temp controller is fine if you have power, but when the heat demand gets higher some can never keep up if they get behind. Of course, larger fans are required after this, but I hope that you never get to where you need them.

I have to use a Vornado room fan to keep my tanks cool, which is fine. I don't care about some white noise as long as my corals and fish are doing well. I also have a few chillers that I can hook up in minutes, but I prefer not do to this if the fans can keep everything cool.