ive been slopping on fsr for the past 4 years and I was just thinking about cutting it with water to spray it on.. Im glad you had good results.. I'm going to give that a shot.. Nothing like a season on the merrimack for the ultimate test of a stain remover.
I have been using it straight as a gel and the stuff is awesome. It takes rust stains, yellow stains at the waterline, literally everything right down to white!!!