Algae clogs pump

I read the other post about leaving out the sponge filter. my simple small system is outside. 2 kiddie pools (50 Gal) --one for grow bed, one for fish. It has been operating well for about a month but the algae is really starting to grow fast as the summer goes on. This algae covers the pump slit inlets until it slows the outflow down enough to affect the autosiphon. any solutions?