I think I can finally claim victory - three nights in succession with no FC loss. CC tested today with a 25ml sample is 0.2ppm or less - one drop cleared the solution. The filter has run for three days straight without gaining more than a couple psi.

So... I'll let the CL drop down to 6 or so, check and adjust pH, and then add some CYA. Back on page 1, when I thought I had 40k gallons, 6lb of CYA was recommended. Now that I know I'm actually around 20k gallons, I assume I should add about 3lb? I guess once I get all my levels within the ranges here: http://poolsolutions.com/gd/poolsolu...try-guide.html then I'm good to go?