Water pump and water temperature

[tobler]

Hi all,
I just set up a tank for hill stream loaches. It's about 40 gallons and two submergible pumps (combined 1500 gallons per hour) provide some good flow. There is no heater. The problem is that the water temperature in the tank is significantly increased. Are the pumps to blame? Anyone ever had similar problems? Any idea for a solution?
I'd appreciate any response.
Cheers Michi

[andyroo]

Yup- pumps will heat up, and will in turn heat up the water. Point one of them towards the surface a bit to maximize heat exchange and put a little table fan blowing over the water surface. Martin swears by the little fan. I'm sure he'll chime in soon enough.
What's your tank lid set-up like? If it's closed then that will increase heat retention as well. Lights too.
A

[Keith Wolcott]

I experimented a bit with this on a 75 gallon tank in a 68 degree room. Three aquaclear 70 (20 watts each) heated the water to 78-79 degrees. If I opened the top, it dropped to 77 degrees. I then switched to a single Tunze pump that moves the same amount of water as the three aquaclears but only draws 11 watts and the water is 74 degrees with the top closed.

I don't know if this helps you, but at least you know what the problem is and that lower wattage pumps and/or more heat exchange on the surface is the solution to cooler water temperatures.

[tobler]

Thanks for your input. Seems like I will have to go for less flow then. Temperatures here in TX are at the upper tolerance level anyways....
Cheers, m

[andyroo]

Just go with high-efficiency pumps (maybe 30-50% more money up front, but you make it back in electricity) and a little cross-surface fan.
Your fish will thank you.
A

[qumqats]

Any particular brands or pumps you would consider 'high-efficiency'?

I'm wondering if the 6 Danner Mag pumps I have are contributing to my higher than expected power bill. ( lets see, pumps, lights, heaters, what else in the house uses power? )