How to cool your aquarium down.

Seemly warmer weather is on the way. A few things before we look at cooling your tank.

1. You do not need to spring clean your fish tank, you may well crash the cycle.
2. You do not need to turn your heater off.
3. It is a lot warmer in the tropics than it is here, it is likely a normally stocked tank will cope fine with any heat we might see.
4. I will repeat, do not spring clean your fish tank.

Cooling down tanks that are overheating

If the fish are acting normally don’t worry.

If they’re lethargic, breathing heavily, or hanging around at the surface then you need to act.

Test your water first, you may have had a spike. If you can’t test your water do a water change just in case.

Increase the amount of oxygen available for a start, but the warmer the water the less oxygen it can hold. So adding air stones, making sure your filter outlet is causing ripples across the surface and a powerhead will all help, but may not be enough.

Check your heater is turning itself off. If that’s stuck on it will be increasing the temp over and above the heat from the weather. Turn off your lights if you can, they will be adding a bit of heat.

Ideally, you want to keep the sunlight out of the room the tank is in. So keep the curtains/blinds closed in the morning, that will insulate the house from the heat outside.

Now comes the parts about cooling the tank. The easiest way is to buy a chiller, they are a great bit of kit if you can afford one.

If you don’t have access to a chiller then consider a fan across the surface of the tank. This will mean you need to leave the lid off, now hot water can increase the risk of fish jumping, so weigh up the risk.

You can do a water change to reduce the temperature, but this will only work for a couple of hours at best, now if it’s 1 pm the temperature might be dropping enough that a couple of hours gets you over the danger period.

You also can add a bottle of ice to the tank, but you will need to monitor the temperature, you don’t want a rapid drop.

Generally, your fish will be fine, it’s not the actual heat that does any harm, but the lack of oxygen in the water. This is a real issue with heavily or even moderately stocked tanks. It’s worth understocking your tank for this sort of reason, you have a lot more leeway. Some sensitive species might have an issue.

If you have a tank that is temperate then they are far more likely to be struggling, in which case it is well worth investing in a chiller to keep them safe year-round.