I have been using salt-away for about 2 years now. When I first started using it I noticed that the tell-tale (pee tube) would get clogged with flakes of salt. I assume that the salt-away was dissolving the salt and the larger flakes/chunks would get stuck in the tell-tale nozzle. The frequency of the clogging has diminished as I have been using salt-away.
It seems to work, only wish I could find it cheaper then at West Marine.
I run exclusively in salt water.
For flushing, I start by flushing the engines (twin Yamaha) with water (use the rinse setting on the salt-away adapter) then after 10-15 minuets switch to soap and wait for the suds to come out of the tell-tale, then I shut the engines down and leave the salt-away in the engines until next time I use the boat.