Regarding the float in the brine tank, how low should it drop? I have a normal amount of brine in my tank but the float does not drop down as low as the brine level. Is this normal? I'm asking because my softener is drawing brine sporadically. I think the real problem is the air check valve and I want to replace it. What's the easiest way? What stage of the cycle should I set when replacing the valve and do I need to relieve the pressure from the softener before removing the old valve?