Easy way to get algae of of my fish tank ornaments?

Ive had a tropical fish tank for about 1 year and a half now and because my tank is near a window and gets quite a bit of sunlight my ornaments ( sponge bob , patrick , gary the snail and sponge bobs pineapple house) are covered in green algae ive tried scrubbing them in the tanks own water but it makes the paint come off of the ornaments is there anyway i can soften the algae so it comes of easier?