My ALK was ranging from 9-11, and calcium, (over my very busy, poorly neglected summer) slipped to almost 800.
(reduced now to 400). This tank has been up and running for about 4 years now, with several feet of plumbing from one room to the next. With my return line being 3/4 inch and drains being 1 inch pvc. Which will now receive regular check ups.