Temperature control query....

pepecat33

The problem is not how to keep the tank warm, but how to keep it cool! I have a 34L tank with 7 white cloud mountain minnows in it. They prefer cooler temps - up to 24C max. The light in my (quite small) tank heats the water sufficiently to not need a heater, and often takes the water temp over 24 degrees.
The fish are ok - lively and quite happy, but as they prefer cooler temperatures, is there any way of keeping the water temp down?
I don't use a heater obviously, and turn the light on first thing in the morning, and off at about 6pm ish - i keep an eye on the temp and if it gets too high (25/26 degrees) i turn the light off.

aunt kymmie

Other than a chiller I have no idea how you'd kept the temp down.

DCR

Cooling a tank can be a bit of a pain. While heaters are relatively cheap, chillers, on the other hand, command monstrous amounts of bucks. However, there are a couple of options:

If the light is the issue, then you have an incandescent light fixture. Florescent lighting does not produce as much heat as a comparable incandescent bulb. Replacing the fixture may be expensive or impossible, however you can get replacement florescent bulbs that screw into the incandescent fixture. You'll find that this helps the heat problem, and brightens the tank as well, as florescent lights release more light per watt than do incandescent (which is actually the root of the problem).

Depending on the size of the bulb / type of fixture, you may also be able to find an LED replacement bulb, which will decrease the heat problem even more dramatically than the florescent will. These bulbs are a little more expensive, and harder to find, but may be well worth the trouble.

If that's not an option, you can get a small, battery-operated fan that you can blow across the surface of the water. This will encourage evaporation, which means you'll have to top off you tank more often, but it will also cool down your water body.