Have never heard of algae sinking large boards.But I have heard of guys trolling having problems with grass or weeds floating.The grass with hit the line off those big boards and run down to the tru trip and foul them up.If its bad enough the charters will have to move to another area with less grass.The inline boards don't foul as much in that grass due to line from board is already below the water line.If running a dipsey can attach a release a few feet below water to catch the grass.Usually see more grass after a big blow or in the late summer.