If you're going to rake this stuff, it's important to follow up with an herbicide as TGW said, to prevent it reemerging from the tiny fragments left behind. Raking seems like a losing battle but, at least it removes the nutrient load, which would become fertilizer for next years batch.
Pond dye would slow down growth of the deep stuff.
The nuclear option - Floridone, would work well to eliminate everything, for a year or more, but would be best done in early spring , when there is a lot less growth to battle.
