TTipsyDragon
Everyones Favorite Reefing Dragon
Things will only use as many amps as it needs. You could hook it up to a 1000 amp power supply and it would be fine if it was 24v (this is with the knowledge that the pump has a controller and not current or voltage controlled).
Think of amps as water. You can be drinking out of a bucket of water, a pool of water or cup. However you are still drinking the same amount of water per sip.
Voltage is simply how fast that water is going (very simplified i know just in case any other fellow EEs out there reading this lol)
