Flounder anglers frequently ask me when they should go from fishing braid to fluorocarbon line. The concern is they are not reading the water clarity correctly. This is no exact science but here is what I do. If I can see my lure clearly in 1.5 feet of water or greater, I fish with fluorocarbon. If not, I use braid. Intensive study of water clarity as it relates to flounder fishing showed me over the last few years it makes a huge difference.
I personally like Stren Fluorocast and Seagaur products.