did the test on one of my old hydros -- got 74% after 6 hours and 78% after 12 hours.... question is, how long do you guys feel is necessary for the best results --- gonna start the test with my other hydros today... thanks, jer

I've heard it say at least 8 hours, but if your redings don't stabilize leave it longet. The thing is, after a while the readings should stabilize and stop climbing/droping. At least that's what I was told once!!! I do my salt test every 3-6 months and I do it for more than 8hrs. I do it on a friday night from like 7pm and open the bag up next day arround 10am. Hope this helps.

ditto - I always leave it overnight.