Ok I have a Hanna and I'm fairly mean on it......but not mean enough to put rubbing alcohol on it, lol. I just rinse mine off and leave it soaking in RO water or whatever...no worries. You will want some thing to calibrate it with though....whether it be their solution or go to the pet store and buy their ph 7 or whatever. I love my Hanna and it very rarely goes off calibration unless I step on it or something.

Chabnoc is right...Cal Mag rules if you use RO water....there are directions on the bottle for soil use if I remember correctly. Of course I could walk accross the room and look at the bottle I suppose........hmmmmm. yay or nay? Ok, yes there are.....you owe me BIG TIME for that one.

You'll use less for soil than hydro so a quart should be plenty for you to decide whether to continue using it or not.