Sponge filters do disturb the surface but don't produce much current in the rest of the tank.
The bubbles plus the waves can reduce CO2 enough to raise the pH of your tank.
By time you factor in the cost of an air pump, airline, regulator (to turn down the air) and check valve, it costs more than a small internal (underwater) filter
Besides, they make that gawdawful noise which I thoroughly loathe.
I prefer an inexpensive internal filter with added foam for baffling the current, as well providingarea for my beneficial bacteria. It's cheaper.....and it's quieter.