Hi Everybody I Am New. Have A Question On Filter, mechanical filter Options

[javanoob]

i have been reading on different kind of filtration

and i read about mechanical filter which removes solid particles like fish poo and stuffs from the tank.

but what i dont understand is, even if you remove the poo and stuffs from the tank itself,
they remain on the filter(let say sponge) and decomposes as usual, and the sponge is in contact with the tank water
therefore ammonia is still release into the water.
unless you are there to wash your sponge everyday, i see mechanical filtration as just a way to provide a "cleaner" view for your fishtank

does anyone see my point ?

just to sidetrack abit,
i am going to have a heater in my tank, but i am afraid of my silly goldfish getting scourched by it, is it possible ?


thats all thanks

[javanoob]

thank alot for the respond

by the way, i read about washing the sponge in aquarium water instead of clear water so as to preserve the BB

may i know why is tt so ?