Your pH is fine, as long as it's over 7.0, don't worry about it. If the pool is clear and the biofilm is gone, then you can let the chlorine stay between 3-6 ppm for now and use the pool. If it's not clear, and you still feel the biofilm, then you need to raise the chlorine back up and hold it there until the biofilm is gone, and THEN let your chlorine drift back down.

If the film is gone and you're letting the chlorine drift back down, then you can either maintain your chlorine level by using the pucks (as long as they don't contain copper--if they do, then take them back), which will add stabilizer and will tend to drive your pH down, or by just using the bleach, which most of us use since it has no other side effect on the pool water. It's your decision, but you don't want your chlorine to be less than 3 ppm, EVER.

If you want to use the Alk up that your husband already bought, you can--but personally I would take it back and get my money back, go to WalMart and buy baking soda, which is the same thing but 1/3 of the price. I'm thinking that you'll need closer to 14 lbs of baking soda to raise TA from 40 to around 90, but don't add it all at once--I'd add a couple of pounds, give it a day or so to circulate, then add a couple more a day until you get it where you want to be. When adding pool chems, it's best not to add a bunch of anything at one time, but rather to sneak up on your target number rather than overshoot it. If you add 14 pounds of ANY kind of powder to your pool at once you're going to get a cloudy pool, and you don't want that.

So..decide if you need to continue the shock again or not, decide which form of chlorine you're going to use, and then slowly raise your TA...and go swimming!!

Janet