I have been using the TFP methodology for several weeks and the water has been super clear. I rely heavily on the CYA chart to determine where to keep my available chlorine levels. My test from a few weeks ago showed CYA at 50 so I was targeting FC of around 6ppm. My most recent test shows CYA has dropped to 40 so I am now targeting 5ppm. I have talked to my pool builder and a couple of people at work who seem to be knowledgeable about pools. All of them are telling me that FC should always be around 1-3ppm and it is not safe to swim with FC above those levels. I also have a vinyl liner pool (which is only two months old) and they are telling me that keeping FC higher than 3 will deteriorate the liner and it will need to be replaced much sooner. I know the TFP method has been very successful for years and years so I was hoping to get some guidance on the safety of swimming with FC above 3ppm and if I should expect my liner to be replaced much sooner.