Ok… I have a Culligan Gold series softener (9×34?) I know that it has appx. 1 cubic foot of resin from reading a shop manual years ago (I might even own it,it’s here somewhere lol) My question is….When Culligan rents you a softener tank (that is not cost effective), how much “resin” is in their rental water softener tanks (ie 2 cu ft, or 3 cu ft) The specs on my gold states what the capacity in grains a unit can handle instead of resin quantity. My Culligan Gold is 17 years old, I have installed a new rebuild kit (piston O-ring gig) every 7 years or so. My cost factor so far (still counting) is $2.50 per week or $10 month (plus cost of salt). Again how my feet of resin in a Culligan “rental” tank (Big galvanized steel tank)…? Eelpoutguy..? lol