We inherited a pool maintained on pucks and as this was my first pool, I found TFP in my quest to understand what was involved in pool care and feeding. Last season (shortly after closing on the new property), I bought the TFT kit and measured CYA levels of >100. Not surprising, from what I learned. I figured I take care of it in the Spring.
Last fall, the pool level was lowered about 18" for closing (about 25%) and was "refilled" by winter precipitation almost to the "full" level by March. Thinking I was clever, I put a sump pump onto the 2nd step and drained another 18". I remeasured CYA and other values. The CYA was still 90-100. Granted, the company that closed the pool put in some floating pucks, but I was surprised.
I refilled the pool last week and used the sump pump to recirculate things. Today, I take a new set of chemistries and find CYA still measuring out at 80-90. So, some progress, but nearly as much as I expected. I tried warming the water used for the test and it made no difference. I currently have "SLAM" levels of FC (FC=25; CC=0). Does that influence the reading?
My full test results today:
Anything here that could throw off my CYA test? My leading hypotheses are that either I didn't dilute as much as I thought with our winter precipitation and my draining/refill; or that the original CYA of >100 was much higher than I figured (I didn't do the dilution test); that there was some sort of layering and that what I drained off after winter precipitation was not mixed with the rest; or that something in my other chemistries is throwing off the test.