Keep on going with the Borax--if 6.8 is as low a pH as your tester can read, you're still probably way below that. Also, if you're using the "disappearing black dot" test for your CYA, and you didn't even get to the first line before the dot disappeared, then your CYA is REALLY high--not low! Look at the scale on the side of the tube--the lower the level in the tube, the higher the CYA. Try diluting your pool sample 1:1 with distilled or tap water,mix well, and test from that sample. You'll have to multiply your test result by 2, but you need to know the CYA level in order to know where your chlorine needs to be (Cl of 3 isn't high enough, I promist!) Take a look at the best guess chlorine chart in my sig...