Benthic barriers have good and bad things associated with them.
The good– a benthic barrier will kill 100% of the weeds they are covering, they are the best way to control weeds exactly where you want, and they don’t use chemicals.
The bad- the use of a benthic barrier can hurt the small microorganisms that live within the benthos layer by depriving them of oxygen, they are difficult to handle due to their weight and size, and they can still float up when gases of decomposition get trapped under them.