Select a heater, you must consider the question of power, generally speaking, takes 10 Watts of power per 5 litres of water.For example, 90 cm long, 30 cm wide and 38 cm deep Aquarium, volume of 100 l,200 Watt heater should be used. For larger, 90 per cent or more of the Aquariumtank, you need to use two 100 Watt heater, and GE to both ends of the Aquarium,even heat, the better.
Now, small aquariums are also equipped with high power heater, but if the heater's performance is not good, the risk is very large, especially when the heater is ina normal "work", the water will quickly become hot, boiling hot even your fish died,high temperature glass tank may burst.
Moreover, smaller Aquarium, temperature changes more rapidly. Heater works frequently start and stop very easy to damage the climate control components, and cause the heater to malfunction. In contrast, large aquarium fitted with low-power heater, only reaches its maximum load, when the ambient temperature is too low, when there isn't.