I put in a 55 gal barrel on the downspout of one of my rain gutters. The rain water comes off of my patio roof which is metal. It has been installed about a month and now my barrel is full of junk and alge. Does anyone know of a filter I can put into the downspout to help with this problem? I thought of using a old T-shirt to filter the water and I just cleaned out the barrel and put in a cup of Clorox to help clean out the barrel when it fills up again with rainwater.

Any suggestions on a filter?