If your pool is 16x32 and rectangular, for it to have 17000 gallons your water must be at least 4 1/2' deep. If it's an oval, your water must be 5' deep. That's the actual water depth, not the wall height. Is that right?

First off, you can fully ignore your CH #. Unless it's reaching into the 400-500 range, it's meaningless in a vinyl pool
Second, don't worry about T/A either. When your pH comes down so will T/A and it's not at a worrisome level anyway.

Simplest way to lower pH as far as I'm concerned is fill a 5 gallon bucket with roughly 4 gallons. Then pour in a cup or two of Muriatic acid. Be sure to wear eye and hand protection and do NOT breathe the fumes. Then pour that into the return stream. Wait about an hour and test pH again. Repeat until pH is in the 7.2-7.8 range (I like 7.4-7.6).

Or you can buy Dry Acid at most pool stores. I like to dissolve it in water in a bucket as well. You don't want it on your hands or face but it's a little easier to use and store than Muriatic Acid.

If you find that your pH keeps rising, which sometimes happens with salt pools, you will THEN want to lower your T/A. But that's only if you need that.