Would a sponge filter be better that a power filter ???

there is no single good solution..

but a well blended combination will provide for a good filtration system

sponge by nature, holes are larger.. so it is not that efficient in filtering out finer debris or thingys or yucky (I always say that to my niece ).. but it is indeed a good home to the good bacteria.. as more holes means more room also means more flow of fresh water also means more fresh air and food too..

in my filtration system, sponge is only part of what I have.. I have a layer of sponge on the top, follow by filtration wool, another layer of finer sponge and lastly follow by a layer of coral..

having the layer of sponge makes my cleaning easy.. I merely pick out the sponge to wash while leaving the rest intact.. of course I will have to wash them one a while, but with the sponge, I dun need to wash them that often anymore..

in my opinion, there really is no comparison. power filters are, by far, more capable of handling the mess that goldfish make than a sponge filter. however, like fi5hkiller stated, they (sponge filters) make an excellent home for beneficial bacteria colonies and can be a great "addition" to a tank that already has a power filter.

another good thing about sponge filters is that you can remove them to another tank/bin in case you ever need to separate a fish from the others or treat them for something. in doing this you would be creating a fully cycled tank/bin instantly.

just my