A usual aquarium pump is an inductive load to the mains. That means that current and voltage are not in phase. It is possible to measure three kinds of power in AC systems. Real power: Thats what the meter in the house measure. Reactive power (I hope its the correct name in English) Thats inductive or capacitive power and it is going to the pump and from the pump in equal amount.
The third is complex power it is the sum of the other two and what you get if you just multiply current with voltage. So it is totally normal that a pump draws 0.3 A current which means 33 watts complex power and thats displayed on a cheap meter. If You attached it to a Watt meter thats measuring real effect it can be 18 watts and maybe even lower.
In Europe we have 50Hz AC and in USA You have 60Hz. That means that an AC pump is spinning faster in the USA and naturally draws a little bit more power. Usually about 25% more.
If You have a DC pump its spinning even faster and draws a bit more. But that means better foam so it may be worth it.
The third is complex power it is the sum of the other two and what you get if you just multiply current with voltage. So it is totally normal that a pump draws 0.3 A current which means 33 watts complex power and thats displayed on a cheap meter. If You attached it to a Watt meter thats measuring real effect it can be 18 watts and maybe even lower.
In Europe we have 50Hz AC and in USA You have 60Hz. That means that an AC pump is spinning faster in the USA and naturally draws a little bit more power. Usually about 25% more.
If You have a DC pump its spinning even faster and draws a bit more. But that means better foam so it may be worth it.
