I personally wouldn't waste the money on any "conversion chemical" except plain, unscented bleach. You are going to need to have your pump/filter working during the conversion, so yes, I would go ahead and refill the pool before you start the conversion. As far as the filter is concerned, your pressure is going to continually rise as the Softswim goops up the filter, so it is going to require frequent cleanings. And yes, once your conversion is complete, you're going to need to use a new cartridge so that your pool isn't continually contaminated with the goop. As far as conversion time goes, some of the forum users have converted in a few days, some have taken a few weeks, but the average seems to be about a week. A lot of it seems to have to do with how high the chemical levels were to begin with--a lower beginning level of Softswim will require less time for conversion than a higher one.

Janet