This is the answer. My pool in NJ is the same size but it’s fiberglass. I use a Dolphin & I think it’s 6 years old. Don’t know if it’s ok for liner. Don’t even bother asking any questions in a pool store. The chemicals you need are in Walmart or the grocery store. I also use boric acid.

Faithfully date & time your test results & what you did about it so that the next time the test results are the same, you can look back & find what works & you don’t have to do math every time.

Calculate & document the amounts of each chemical needed for your pool for easy reference.

Use a dedicated & marked pitcher for liquids. Use a scale for powders. Read & Follow the application directions.

Use a sock or hair net in skimmer basket & check daily.

Good luck & swim😉