Fish Mix

[KittyKat]

It's the summer, so the water will try to match the air temperature.. the best easy thing to do is keep lights on for only a couple of hours per day (lights heat produce heat), provide good ventilation (so maybe leave the lid open) and make sure direct sunlight never touches the tank. If the room gets stuffy-hot, open the windows.

If you have a fancy goldfish only tank, they will not need a heater, the water in a larger tank can maintain its own temperature overnight well enough and the average house does not get colder than 15-16 C in winter.

The average house is the problem, I'm quite high up in the hills so the heater is being cautious it can get to -5 in my house over night until the heaters come on in the morning.

Heater sounds like a must, in that case. If you can get one which will do 16 or 18 C as the lowest, it should be fine to leave it on the lowest, but because your house gets that cold, I recommend two 100w, or maybe even 150w, heaters, one at each end of the 150 litre tank, so they maintain constant temperature throughout the water.

 

[ProjectMayhem]

It's the summer, so the water will try to match the air temperature.. the best easy thing to do is keep lights on for only a couple of hours per day (lights heat produce heat), provide good ventilation (so maybe leave the lid open) and make sure direct sunlight never touches the tank. If the room gets stuffy-hot, open the windows.

If you have a fancy goldfish only tank, they will not need a heater, the water in a larger tank can maintain its own temperature overnight well enough and the average house does not get colder than 15-16 C in winter.

The average house is the problem, I'm quite high up in the hills so the heater is being cautious it can get to -5 in my house over night until the heaters come on in the morning.

Heater sounds like a must, in that case. If you can get one which will do 16 or 18 C as the lowest, it should be fine to leave it on the lowest, but because your house gets that cold, I recommend two 100w, or maybe even 150w, heaters, one at each end of the 150 litre tank, so they maintain constant temperature throughout the water.

Thats not a problem I like to max everything anyways, my filter is a 250 litre filter on a 150 litre tank so the heater will be for a much bigger tank also.

 

[KittyKat]

Thats not a problem I like to max everything anyways, my filter is a 250 litre filter on a 150 litre tank so the heater will be for a much bigger tank also.

That's not the best attitude to have.. goldfish will benefit from it, but a delicate fish which would struggle against the flow would not. A better attitude would be to provide the best conditions you can.