I have one, it took 4 months to get stable... if you're not set on this one, I'd recommend looking for other options as well. I originally thought, hey at that price I can buy 4 before I spend the same as the others... but the noise is driving me nuts!
There's no way to bleed gases out of the chamber and the air/gas mixture gurgles... so the only way I've found to bleed it is to run if full on, and that'll drop your pH in the main tank... especially if you forget to turn it back down...