It is only my recent understanding that there is no real requirement for CH in a vinyl pool. What about vinyl with an SWG. I was getting ready to order CH again, should I? thx, SR

There is some debate on the value of CH for vinyl lined pool. That is one reason why the minimum recommendation 50 ppm CH. http://www.troublefreepool.com/pool-school/recommended_levels

I'm not certain, I know what you're asking. As for an SWG and vinyl, there isn't any problem, there are number of people here that use SWG's and have vinyl liners. As for the CH, its not really a factor for SWG's either. As for buying more CH, if you are with in the recommendation (see above) I wouldn't buy or add any more.