First off, double check your pH. If you are still unsure, take a sample to a pool store. If it is STILL insanely high you'll need to bring pH down using Muriatic Acid. You want it no lower than 7.0 and no higher than 7.8...but lower is better then you'll want to shock it to 20-25ppm...25 ppm shouldn't hurt your liner if your CYA is 85. But your real goal should be 20. Start there.

But adjust pH first because high FC levels give false high pH levels.