2 lbs of CYA will raise your 7200 gal pool to 30 ppm which is the lowest that many tests can measure. I would add another half pound (scant half cup is close) to bump the level up slightly in case your test is just not registering it.
Wait a week until you test for it since sometimes it does take a while to show up and be sure NOT to backwash from the time you add until you test to be sure not to accidentally backwash it away.