Wow...this is a job for the experts

[chem geek]

I am surprised since the alk is so low, I thought the ph would swing up more quickly.

If the pH were 4.0, then it would take about 5 boxes of Borax to raise the pH to 7.0 and almost 7 boxes to get to 7.5

If the pH were 3.0, then it would take about 11 boxes of Borax to raise the pH to 7.0 and 13 boxes to raise the pH to 7.5

So it would seem that you need to keep going. If you use Borax, then you will end up with high levels of borates in the pool. Each box of Borax adds about 3.6 ppm Boron (Borates) to the pool. So a positive side effect of raising the pH in this pool is that it will be close to having the algicidal properties of the pool that is talked about in this thread.

Richard