If it is that thick blanket weed that sticks to everything like shit to a blanket then I personnally would do more than just bag my baits and hope for the best.
Once the bag melts, the constant movement of water, attention of small fish and any slight pull will feck up your presentation big time.....its allmost a waste of time.
In that stuff (and this is just my very humble opinion) you have got to reach for the spod rod, a nice BIG bucket of mixed particles (15-20 kg +) and 4 or 5 kilos of boiled baits and just un-load on the spot.............let the fish do the rest, after a few session