96% is fine to use. I actually prefer the HTH brand from Walmart as it dissipates from the stocking in front of return much faster than any other brand I've ever used, especially if you massage the stocking a few times. It, also, seems to dissolve into the water much faster. (Be wary of all the other Walmart chemicals as many have copper in them. I prefer their metal sequestrate, as it seems to do some work on the scale. The bottle states to use this product with the HTH chlorine content sanitizers. That's because of the copper content which can eventually leave copper staining on pool walls and floors.) You may want to put in a little less than called for as I just recently got higher CYA levels, in two pools, than what I measured for. It wasn't drastically higher but, in both cases, I used several lbs less than pool calculator called for, to start. I think, also, since it seems to dissolve into water faster you can get a reading in a few days instead of a week. For both pools the pump was run 24/7. (In both cases we could consider pool volume inaccuracy, but the first pool calculated volume is pretty close as determined by results from adding other chems but I may have calculated the second pool volume a little high but it shouldn't be off much. Initial pool calculator called for 4 lbs more than I added and it went from 0 to 50 in four days. Also to consider, for the second pool, that the 0 reading of CYA was actually somewhere between 0-20 as it is hard to get a really close measurement with the CYA test.)
If you want to massage the stocking(s), in front of return, for 30 seconds or so, several times the first day, you can actually get it all into the water the first day. It will come out of the stocking as a very, very fine powder and disappear quickly into the water. I've taken reading three days after stockings have emptied and gotten accurate readings.
First pool I used heavy women's tights which worked great. Second used regular women's knee high (I've done the knee high and tights more than once) and the hose does tend to run letting some granules out rather than only fine powder when you massage.
For the second pool I put two lbs of CYA in four stockings, in front of four returns. This is my friend's pool so I couldn't be there to massage the stockings. The stockings are tied to bricks sitting on edge of pool. My friend knocked one brick and stocking into the pool. When I went back over the next day three of the stockings were almost emptied. The one that fell in looked as it did the day I put them in. I massaged that bag a total of 3 minutes and got all of it emptied.
I have pretty delicate skin. I massage the bags without gloves on and never seem to have any problems with my skin. I do rinse my hands off and put lotion on afterwards.
Edit - As the metal sequestrate at Walmart is some much cheaper than others I've used I do tend to use more of it. I used it all winter after an AA treatment. That may be why is has continued to lift the scale.)
gg=alice