Thanks so much, folks. The help was priceless
Made it through to the end of the season next week.
Based on what I learned here, I have the TF kit now and will monitor using that
Looks like the unanimous outlook is that sand in a sand filter does not need replacement.
I also learned when the pool turns cloudy from green, the cloudiness reduction movimg forward is a function of the filter doing its job over however long it takes to get the water clear
Question - what would be signs that a sand filter is performing at peak levels or is struggling keeping a pool clean?