Wal-Mart shock

[RknRusty]

I have a 24' ab vinyl pool. The shock that seems most effective for the past few years is the stuff at Wal-Mart, sodium dichloro s triazinetrione. I see this year they have it with copper, which I'll need in August when the pink slime and mustard algae attacks (usually after a beach trip). Is this chemical okay?

My pump runs 24/365 and the water was clear all winter. I live in SC. When I started adding chemicals this spring, I first balanced the PH, added some maintenance algaecide, then added pucks to the chlorinator and shocked it the next day. The store told me I had no free chlorine and to add 15 bags of burnout. No way, said me. Could this wal-mart shock cause my chlorine to bind?

Their test results:
CYA 40
TC 3
FC 0
PH 7.6
TA 176
TH 114 (yeah I know it is not necessary)
Copper .1