kinetico water softener

I am pretty handy, installing and servicing many softeners for neighbours and friends, and find the EcoWater (kenmore, Northstar etc..) machines simple to work on. I have a kinetico ( I think model 30??? not very old, its about 48" high 4 tanks, side by side and stacked one on another, with a seperate brine tank. ) I want to replace the carbon in the top tank, but would like some instruction before I begin messing with it. Also, it has a wheel #2 in the head, what does this indicate? Thank you for any help that you can extend. I already have the coconut shell carbon, and am anxious to get started. Ed

I would think you take the control valve off its tank and the tank adapter off the other tank and suck/pour/flush out the carbon, maybe sanitize the tanks and rinse them and add the new carbon and put it back together and backwash both tanks.

The #2 is a disc that establishes how many gallons between regenerations.