Help raising PH and TA

Assuming your numbers are correct and that the pH is really 7.0 (TA is 70 and CYA is 55), then it would take 85 ounces weight (5.3 pounds) of 20 Mule Team Borax in your 26,000 gallon pool and will also raise your TA to 77. If you already had some pH Up (sodium carbonate or Washing Soda) product and wanted to use that instead, then you would need 43 ounces weight (2.7 pounds) and this will also raise your TA to 82.

Note that if you are starting with a pH of 7.2, then the above amounts will raise your pH to 7.66 which is why the calculation is not straightforward. It depends on your starting pH, TA and CYA levels (and Borates, too).

The safe thing to do is to add less then you need, let it circulate and equilibrate for a few hours, then retest (or just test the next day).

Your low CH is not a problem at all, since you have a vinyl pool. You only need to be concerned if it gets around 500.

pH does not 'bleach out' with high santizer levels when using liquid reagents but can read higher than it actually is because of a chemical interaction between the pH indicator and the chlorine or bromine in the water. If you were getting pH readings of 8.0 or higher I would suspect this interaction but since your pH is reading low I would start raising it.

Now that you mention pump parts, I seem to recall something about heaters... I don't know about either, only that a liner pool does not have a Ca requirement.

Someone else will be along to add to my lack of information!!