Can anyone guess how much heat a tiny pump generates?

[knifegill]

I suppose I'll end up just testing it anyway, but I have a tiny pond-style pump, probably from a mini-fountain or something, that I'd like to use in a betta setup for biofiltration. I'm wondering whether it will generate enough heat that I won't need a heater, or if a baffled powerhead would be a warmer option. It's a RIO 50, 262 e/hr, 5.3 watt. Is the weird 'e' thing for liters? Anyway, I'd have this little pump in about three U.S. gallons of water. Any guesses at thermal contributions? I can always scrounge up a heater if I have to, but the thought occurred to me about pumps being warm.

 

[knifegill]

OMFG. This RIO 50 is a mini-BEAST! I've got it in a plastic tray in about two inches of water and it's running. It moved like a motorboat across the tray when I twisted the cord to place it after plugging it in. The opposite side of the water is a tall roll about 3/4 of an inch tall above the waterline. If this doesn't heat the water, I don't know what will.