The polyquat creates a chlorine demand of its own, so I'm not surprised that your chlorine now is zero--but you can't let it stay there long I suspect that your chlorine is also working pretty hard on the stuff that's in your water, so it's probably going to take some diligence to get chlorine to hold for awhile. You can keep the trichlor in the floater, which will help feed chlorine in pretty constantly--just keep an eye on your pH. Otherwise, the dichlor would probably be okay, but honestly I would go with plain, unscented bleach. With all the other things you have going on in the water, bleach is the least likely to complicate things worse than they already are. Besides, it's much easier to calculate doses. What is the volume of your pool?