Stan Meyer did say you could use salt water in his cell but he didn't mention anything about sludge, etc... so maybe that was up to everyone to figure out for themselves.
For electrolyte before, I did try Red Devil drain cleaner once and added about 1/2 tspn for 1 gallon of water...that was a LOT!! It was drawing almost 5 amps at only a couple volts but without it, I could get about 30+ volts at 5 amps so it is super conductive.
A few have tried calcium hydroxide to speed the calcium coating on the cathode. Kalkwasser powder at aquarium stores might be a cheap source for that. I think Adam Ant can comment on that one since he owns a pet store or aquarium store??
I'm working on something with no conductivity at all.