I had no luck with my wrasse eating the FW infestation I had. 1 Solar, 1 Exquisite, and 2 flashers.
I think it was b/c these are plankton(water column) feeders.
I got a leopard wrasse about a month ago and the flatworms were gone in about a week.
I'd wager that the 6lines are fine, but then you can't really add more wrasses.
People have problems with the Leopards, but I was able to find one that ate frozen Mysis in the store. For a while that was all he would eat. Then bloodworms became "acceptable", now he will eat anything but pellets. Formula 2 flake, cyclopeeze flake, DIY frozen mix... but I digress...