filter output question

[marisa]

We have some fancy guppies with long long fins and they seem to get disturbed and sometimes worn out by the fairly strong current the filter makes...teh filter is not too large for the tank but the current is still a bit stronger then it should be i think....anyways....someone told us we can shove a piece of sponge in the filter UPtake to slow it down. I did not think this was a good idea...but can someone here tell me?

Or tell me what can be done to lessen the current created by a filter in a small tank?

Marisa