If you decide not to drain/refill to lower the CYA, you are going to need to shock the pool to overcome the bloom that's trying to happen--but with your CYA that high, you're going to have to raise your Cl to 25 ppm to get to an effective "shock" level. Once the pool has been shocked, you can let the chlorine drift back down again, but it's going to have to stay at 8 ppm or above for the rest of the season in order to not risk more problems. That's why Watermom is suggesting the partial drain and refill--to lower that CYA so that your Chlorine levels are more manageable.

Janet