PH low after adding my cya- how to adjust?

[LindaE]

Did my conversion in less than 2 days and my pool is beautiful; however, this morning my ph was down to 6.8 after adding 4 lbs. of CYA in the skimmer. The bleach calc says to add soda ash to raise it and other threads say to use borax. I am totally confused as to what to add. What is soda ash and where do you get that? Also , is this normal that the cya lowers the ph?
My pool is an IG 18000 vinyl liner. Had to use test strips and they are hard to read, but I haven't gotten the kit I ordered from Ben yet ( which was only 4 days ago). Should I get a drop based from Wal-Mart in the mean time or can I continue with the strips and guess at their accuracy?

CH 1
Ph 6.8 (yesterday 7.6)
AlK 100
CYA - don't know yet

Help! Linda

P.S. I used a kitty litter scoop to clean a lot of the gunk out of my sand filter until I can change the sand. It worked really well because the globs stay in the scoop and the sand just falls through when the filter is not drained of water. (Sorry if this tip is in the wrong thread-I am a newbie)