Alge

This is my 3rd year for having my pond, small 5 x 4 foot, 36inch in the
deep end, 18inch in shallow.

the first year I had clear water, running a UV filter, no alge what so
ever, the second year still running the uv filter, the water is clear, but
alge is now on the sides and rocks of the pond (im talking long strands of
alge) , now the 3rd year and I still have the alge with clear water.

How do I get rid of this alge and keep it from coming back.

I do have fish and no plants in the water.

The only filter I have is a large sponge attached to my pump.

The pond does get sun.

I live in Toronto, Ontario, Canada

Oh.. I have other friends who also seem to have this problem which started
last year also, and they look to me to solve their problems also.

Any suggestions ?

joel.