This is my first year with a pool and the pool store talked me into the Sustain (Cal-Hypo) system. I purchased what was supposed to be enough for the whole summer & I have maybe enough chemicals to last me another week or so. I would like to make the switch to the BBB method. I have a Taylor TF-100 test kit just want to know how I go about switching. I read a post somewhere that said something about a possible problem switching with the summer sheild product added in the same year. I put a jug & a half in the 3rd week of March. Will that cause any problems? My water is clear & has been all year.