I agree with CarlD. Just add a little straight cya and don't fool with the trichlor. The good part of just adding cya is that after a week or two of tweaking it, you will seldom need to test the cya level again - maybe only a time or two during the entire swim season. When using trichlor, you have to continually be checking the cya level because it will quickly climb and without realizing it, your level will be too high. I always just add the cya and forget about it. Too easy. Easy is good!

Watermom