First, I came across poolsolutions and this forum the other day and am overwhelmed by the wealth of information!

Several years ago we purchased a house that already had in in-ground vinyl liner pool with an automatic in-line chlorinator. The previous owner had bought into using a boutique brand of chemicals called Sustain, manufactured by PPG. The automatic chlorinator is a PPG/Sustain model and accommodate 3" tablets.

After doing some research the Sustain tabs are basically calcium hypochlorite tablets, not the commonly found tri-chlor tabs. Interestingly, PPG manufacturs essentially the same tablet (with possibly a different erosion rate) under their commercial Accu-Tab lablel. For a few years I was able to convince a local pool store to order me the commercial Accu-Tab tablets even though I wasn't a commercial account. For whatever reason the local stores I've dealt with can no longer order the Accu-Tab tablets.

With that background here are my questions:

1. I've seen warnings about not using any other tablet in the chlorinator but how serious is the risk? If I just let water circulate through the chlorinator for a week or so can I then use 3" tri-chlor tablets in the chlorinator?
2. Does anyone know of another source of 3" calcium hypochlorite tabs?
3. If I can't use tri-chlor tabs, and I can't locate calcium hypochlorite tabs, would it be worthwhile to change out the existing chlorinator with one that can use tri-chlor tabs?

Thanks.