5 Boxes of Borax later.... PH STILL very low

[doggie]

Help please! This is our 1st year with BBB. We opened the pool last Saturday, 3 days ago. First thing I checked was the PH, and it was less than 7.0. So having no clue how much Borax was needed, I added a box and retested in 2 hours. No improvement. So I added another and retested again... still way too low.

So far as of yesterday I've added 5 boxes and the PH is still registering under 7.0. (see comment about the test level yesterday below) We have an inground 25000 gallon vinyl pool.

The other numbers last night after the 5 boxes of Borax were:

FC 8.0
CC 0
Alk 160
PH 6.8 (according to the simple OTO and also strips I checked with )
CYA 0 (was waiting to add until I was sure we wouldn't need to backwash for a couple days)
Cal Hardness 150 (I didn't write it down, but I'm sure it was right in that area)

Please don't chew me out for not getting the Taylor PH, I assumed the liquid part of the OTO test would be OK and I have 2 bottle of solution in the fridge that I wanted to finish up first. In addition, I used 2 different brands of test strips, neither of which is past the expiration date. And all 3 consistantly gave me the same readings.

Yesterday the PH had gotten up into the 7.6 range (again all 3 ways I tested matched each other), but today when I tested (all 3 yet again), its right back down to under 7 much to my dismay.

The only thing I've added besides bleach and Borax, was one 5 pound jug of PoolTime Shock plus Clarifier. I added that PoolTime shock right when we opened. Other than that, nothing else.

Also, the water is crystal clear.

Help anyone?

Edit because I forgot to say I just went out there and added 2 more boxes. I hope that wasn't a mistake. I did that before thinking of making a thread