Hi, I've had my pool ~5 years now, and this year I am testing it after doing some maintenance and cleaning the filters, etc... I've never had any problems with it, and not once have had algae pop up (I'm quite proud of that!).
I use the CL tabs, of course, and so I know my CYA levels are really high. In fact I just did a test (using a TFP test kit mind you!) and it showed CYA levels in the hundreds, probably like 400-500 I'm estimating, since there's no additional hash markers on the vial.
I am also noticing my CL test shows ridiculously high CL levels. The color is more of an orange in fact. Well off the chart.
So I am thinking the high CYA level might be screwing up my CL test, is that possible?
I'm planning to drain the pool (soon) maybe down to 1/2 or so, and refill with new fresh water.
I'm not sure if I will continue using the CL tabs/pucks, because I like the convenience. I don't mind having to drain my pool once every few years (this will be the first time in ~5 years btw). I tried the BBB method for a bout 6 months but I stopped doing it. I can't remember exactly why I stopped, but I vaguely recall the liquid Chlorine is more expensive than the tabs, and doesn't last as long (I have to add CL more regularly, whereas with the tabs I can go for 1-2 weeks before I have to refill the cylinder).