I'm honestly about to just buy a small float switch and rig it up to an aquarium pump lol. Several hundred GPH will drain a bucket very quickly and pull less than 100 watts.

Edit: just found this actually. Might be a good option for a regular old aquarium pump.

Edit 2: ended up getting the "basement watchdog" linked above. That's it, that's the solution - that little device is absolutely perfect for my use case. You can plug an aquarium pump straight into it. If anyone comes across this comment looking for a similar solution, I highly recommend the basement watchdog float switch device.