How do I keep my water temperature low?

[T Money]

I'm aware of how heaters regulate the temperature of an aquarium. But what if I need to cool my tank? My tank currently sits at 75 degrees and I believe they need cooler temperatures. I have 4 goldfish in a 30 gallon tank. How do I keep my water cooler than the room temperature?

[Fresh2o]

Lower cost option is to run a fan across the surface. It will increase evaporation.
There are chillers you can use. These are effective but can be expensive.
BTW 75 F should be fine for the four goldfish. I’d worry more about eventual crowding as they mature (and get large).

[BBradbury]

Originally Posted by T Money

I'm aware of how heaters regulate the temperature of an aquarium. But what if I need to cool my tank? My tank currently sits at 75 degrees and I believe they need cooler temperatures. I have 4 goldfish in a 30 gallon tank. How do I keep my water cooler than the room temperature?

Hello T...

You're right about the temperature for your Goldfish. 74 degrees is really too warm. Goldfish are cool water fish and 70 degrees is the warmest for them. 65 to 68 degrees is optimum. You can lower the thermostat in your house to 68 and if you have a heater in this tank, remove it. In warmer weather, you can set up a floor fan and point it in the direction of the tank. Large, weekly water changes will keep the oxygen level in the water steady. As we know, warmer water doesn't hold oxygen as well as cooler water.

B

[m.j.gomez]

Hello, I started a 55gal goldie tank & been researching on how to keep it cool in summer. Came across a diy that uses a mini dorm fridge & canister filter. Priced fridge at 80$ & penn plax cascade 1000 canister for. 129-79$(these are new I'm sure you can find cheap used online).
I also read that people use frozen water bottles set next to filter(a little worried about temp swings). Hope this helps!

[Delapool]

I’ve seen somebody set one of those up here and worked alright. Could control water flow from memory, I’m not sure what was used.

[Fresh2o]

I like the mini fridge and canister idea. You could probably swap out the canister filter with a water pump or power head. You would have to fashion some type of radiator in the fridge for heat transfer.

[Mcfly]

I made a custom hood... It's overboard, but works. A temperature switch turns (2) high
power CPU fans on at 78*F, they have acrylic diverters that push the air across the top of the
tank. This creates evaporative cooling. The fans shut off at 75*F. This allows
me to keep the tank covered to avoid fish jumping ship.

The tank looks like your typical hooded tank:



But when you get up close, you see the fans, and vented light hoods:

[T Money]

Originally Posted by Mcfly

I made a custom hood... It's overboard, but works. A temperature switch turns (2) high
power CPU fans on at 78*F, they have acrylic diverters that push the air across the top of the
tank. This creates evaporative cooling. The fans shut off at 75*F. This allows
me to keep the tank covered to avoid fish jumping ship.

The tank looks like your typical hooded tank:



But when you get up close, you see the fans, and vented light hoods:

Wow. That's pretty cool

[Mcfly]

It works surprisingly well, though it does evaporate a fair amount of water in the summer.
Located in Florida, so keeping things cool can be challenging.