I bought my first pontoon about month ago, and it has a 2005 evinrude 40 hp etec outboard water ready. Put it lake for the rest of season & I started to notice algae type crud attaching to the lower unit. First could that build up & block the water passage to the impeller. The motor is to heavy & the way the back of pontoon is cannot be tilted out of water. Second ( maybe not politically correct) but what a idea cut window screen & place around the area of the water inlets & attach zip ties around top & bottom. I've read up on motor it seems like a fantastic motor & I don"t want to hurt it. Thanks for any advice