thanks pat..i wanted to get on with it and there was a good sale on the crystal plus (.30 cents per bag off the price when i went to canuck tire today..3.69 a bag) i bought 10..only needed 7 plus the amount already there to bring it up to 3800 ppms which sounds pretty close to right for my autopilot once i get her going i think. it was easier to deal with then i thought..i dumped 3 bags at a time right over the main drain and without about an hour total, it was all dissolved. the purity was 99.8%..didn't say anything about any other ingredients but i was brushing to be on the safe side. all is good..can't wait to get my new system going after about 7,000 worth of equipment including the 2200 in electrical and heating labout that is to come, purchased this year to bring my pool up to modern times.