Hi first post, I have a 20x40 pool always had no trouble with it, now i find the ph won't go up after using a7 pounds of ph raiser from pool place and also ALK is low too using the strips new packet of them to.thanks
The common PH tests will read anything below 6.8 as if it was 6.8. If your PH started below 6.8, it could be going up without any visible change in the test result. 7 lbs of PH Up in a pool that size isn't really all that much.
It is also possible for the strips to be wrong. If you can get a double check that would be good.