Stabilized chlorine will increase your CYa levels very, very quickly. In fact, if it's dichlor you've been using, it adds 9 ppm of CYA for every 10 ppm of chlorine!! The algaecide and phosphate remover don't affect your stabilizer levels, but they DO create a chlorine demand, which is probably one reason why you have algae you can't kill.

In order to shock your pool, you look up on the chart what your "shock" level is, depending on your CYA. For example, for a CYA of 140, you need to attain a chlorine level of 25 ppm. Then you need to hold it at that level as consistently as you can by testing and adding more chlorine as needed to get back up to that 25 ppm. The more consistent you are about keeping the chlorine up, the faster the pool will clear. You need to maintain that level until you can measure your chlorine at night and again in the morning before the sun hits the pool, and not lose any chlorine during that time. At that point, you'll know it's time to let your chlorine drift back down, but with a CYA that high, you never want it to get below 8 ppm.

Janet