We really need some numbers taken with a good kit to be able to offer advice. If your CYA is off the chart, you're going to have to run higher chlorine than most kits can read. Go to the test kit link in my signature below and order a Taylor K-2006 or 2006C (better buy). When you repost with your numbers, give us details about your pool. Type of pool and volume, type and size of pump and filter. Then somebody here can try and help you.

You do NOT want to totally drain a pool.

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