For marketing reasons, the SWCG manufacturers tend to emphasize no other chlorine -- but that's mostly a matter of trying to sell how easy to use they are. "Boosting" shortens the life of your SWCG significantly, I believe.

Instead, just use bleach, added in the evening, till you have everything under control.

As far as testing goes, so long as you can't test your own water, you are at the mercy of pool store's often inaccurate and always sales-driven testing. Go get an OTO / phenol red kit for now, and please order a Taylor K2006 or 2006C FAS-DPD kit.

Meanwhile, use bleach as Aylad suggested, and stay away from other adjustments, so long as your pH is between 7 and 7.8.

Ben