We got our Taylor kit this week and used it to test our existing hot tub (450 gallons). CYA was super high so we drained tub completely ( pool store had us using dichlor so now I know what NOT to do!). We used pool math and added stabilizer shooting for 40. Somehow we overshot and we need your advice. Here’s today’s results:
FC 5.5
pH 8.2
TA 250
CYA 80
Temp 101.
Should we drain hot tub? Or just increase the FC to the recommended levels?
FC 5.5
pH 8.2
TA 250
CYA 80
Temp 101.
Should we drain hot tub? Or just increase the FC to the recommended levels?
You sure did go over a bit. Ha. 
You might consider exchanging about half the water which should bring the CYA down to a much more manageable level. Trying to manage the pH in the hot water with an elevated FC level to compensate for that high CYA might just be problematic.