Hey everyone, I've got a weird pH issue. Running a 3871 gallon Intex vinyl pool with a SWG, and the pool water has remained (and still is) crystal clear. Initially I had trouble keeping the chlorine level above 1, but after 1/3 pound of dichlor and continued daily operation of the SWG, it's staying in the 4 to 5 range.

My problem is pH. It's always been on the low side, 6.8 to 7.0. Yesterday I added about a cup of borax and it barely budged. Today I added two more cups and it shot up to the 7.8 to 8.0 range. Testing was done about an hour after application. What did I do wrong? Browsing around this board I see people adding entire boxes of the stuff and barely getting results. Did I just not wait long enough before doing the second test?

Additional information: I added the borax by slowly sprinkling it in at the return jet (because I don't have a skimmer basket). I am testing chlorine and pH using the HTH 3-way test kit.