Welcome Mary!
Before we talk drain and refill, I believe you need to do some reading - that way, you understand how your pool chemistry works and why you would need a drain/refill.
TFP methods teach you what your water is made of and how those things interact. So you begin in :lookhere:
Pool School! Below "Getting Started" is a section called "Pool School Index" with a wealth of information! You should begin with the ABCs of Pool Water Chemistry. Learn about CYA and it's relationship to chlorine levels. It's a plethora of knowledge and quite overwhelming in the beginning. Read it. Then read it again. I promise it begins to make sense.
Those testing results look very much like pool store results. You will find by reading here that pool store results are notoriously inaccurate. The same with test strips - useless. A good test kit is a wise investment for you! :lookhere:
Test Kits Compared - the best way to know your results are accurate are to do them yourself. Test Kits Compared will show you the different types as well as roughly how many tests they can perform. I personally recommend the TF-100.
This may not mean much until you understand the CYA/Chlorine relationship but this is the test most often ill performed by pool stores. You have a result of 100 - it may very well be much, much higher. CYA does not go away except by way of drain and refill.
So do some reading and please come back to this thread when/if you have questions and I'm sure there are plenty of folks willing to help get you a clean, clear
and well sanitized pool!
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Oh, and if you would be so kind, please update your signature to include your pool and equipment specifics. It will help everyone to answer more questions without having to search for that information each time. Thanks so much!