PlanetCatfish.com

I've fitted some of my tanks with small powerheads (AquaClear 201 and Eheim Aquaball without filtermaterial) to give my Scleromystax prionotos, barbatus and C-113 some serious watermovement as I think they seem to like this a lot. I also noticed that some people here use internal power filters for these species.

My problem is that the temperature rise quite a bit to 25-26 degrees Celcius instead of the 22 I would like in the tank. Is there any powerheads that heat up the water less than others? Any idea how to get around this?

When I installed a tank (300 liters) with internal filter (2500 l/hr, 38 watts) I had, just as you, not expected to see the temperature raise

However, a submerged pump has no other coise than to give all excess heat to the water, and all energy used to displace the water will due to friction result in more heating of the water.

In the end, all 38 watts will be used to heat the water, resulting in a temperature difference for this tank of 5 degrees (C). For me this was welcom, and an argument to use more big pumps, because, if the water needs to be heated anyway, way not heat the water through the pump, getting more current and heat for the same energy price

However, for Scleromystax warm water is not good, and the only solution is to use pumps which consume as little power as possible, or external pumps - preferably not placed in a closed under the tank, off course

Tunze turbelle classic powerheads are really good even
though they look kinda "old-school". They're installed over water to the side of the tank and atleast my reeftank back in the day lost most of it's heat problems as soon as I installed these pumps. They're also surprisingly quiet and have a pretty good output/ wattage ratio. It's also really easy to turn the basic intake into a sponge filter.

Only bad side is that the smallest model puts out
2400 l (634 US gallons) /hour, so they don't fit the
smallest tanks.

My turbelles are about 10-15 years old and still run smooth and quiet.

Thank you both

I will look for lower wattage powerheads...the Tunze-solution is a bit hefty for 30-45 litre tanks

Expensive magnetically coupled circulation pumps that mount the motor externally are available.
VorTech Propeller pump MP40 flow adjustable from 100 gph to 3000 gph $344.99.

I would look at some other way myself but the technology exists.

Vigorous aeration is likely to prove sufficient without adding heat to the system.

Using an external in line pump would be another way to provide low heat transmission. MaxiJet Power heads may be mounted in an inline nonsubmersed configuration for low cost.

Thank you Larry, I'll se if that brand is available over here, or I might try ebay or something.

Was thinking about a small outside canisterfilter like the smalles Eheim Ecco.