As you can see in my sig, I have a vinyl above-ground pool, so I don't test the calcium hardness very often.
Back on July 8th, it was 110. I didn't test it again until the 20th, a couple of days after I had SLAMmed my pool. I only registered 20.
I haven't drained the pool or replaced a lot of water either. I figured "eh, you screwed up the test. Get it right next time."
Today was "next time", and I got 20 again.
Should I be concerned, or is this a "non-issue" since it's a vinyl pool?