Jury is still out on the speed of media usage for me. It’s only been running about 3 weeks now. I got one of the jumbo reactors from BRS and the first full lasted about 2 weeks before I noticed the pH trending lower. I refilled it just before I went on vacation so I’m hoping without me in the house for hours each day it will last a little longer. I think if 2 weeks is the average for me, the 7lb bag of media would last me about 6 weeks @$35 or so per bag. I should add that I also drilled holes for a couple of 1/4” tubes to the outside that I now use to push air to a couple of air stones in the sump. I now have them running into a standing piece of PVC so most of the bubbles don’t get into the sump. Originally I had it feeding the skimmer intake and only saw a 0.02-0.04 average improvement in pH, and would still range from 7.9-8.07 on a daily cycle. After the scrubber it stays stable higher. I have the pH probe on the CaRX set to 6.5 currently.