Clear water, zero FC

[UnderWater]

I've read all the relevant posts regarding chlorine problems and they are interesting.
I'm not familiar with all the abbreviations so I'll spell out.
My pool is in-ground, vinyl, 33,000 gallons.
Water is clear as a bell, ph is perfect.
I changed the filter sand this season, from medium to fine.
Cyanuric Acid (stabilizer... CYA?) is a bit high. 60 ppm
Two nights ago I added 3 lbs of power plus shock to the skimmer and put a 3" tab in the skimmer. This was after 2 weeks of adding 2 lbs of powder shock every few days with no joy.
I'm still reading 0 ppm after reagents 1 and 2, and .5 (or less) after reagent 3.
The pool stores (Leslie and Pool King) both say shock... 2 lbs.
I have an in-line chlorinator set to the max. It holds 12 3" tabs.
Help! Please.