Just want to make sure I'm all good

[angiv]

Thank you so much! What should I use to increase the CYA?

[PoolDoc]

Either dichlor, or stabilizer. Undiluted dichlor is about 55% chlorine & 50% stabilizer (not a typo: I know the numbers total 105% -- very LONG explanation will be skipped). The problem is that stabilizer, as sold by pool stores, Walmart, Costco, etc diluted with various ingredients, some of which can cause real problems. Here are two undiluted sources:

24 lbs PoolBrand bagged shock @ Sams Club
Kem-Tek Dichlor 22 lbs @ Amazon

Stabilizer -- cyanuric acid -- is easier to find, but is hard to dissolve.

If you'll complete the pool chart, we'll be able to help you with doses:

Pool Chart Entry Form

[PoolDoc]

Just saw your first post -- with a 1600 gallon pool do NOT get a bottle of dichlor, like the Kem-Tek. The bagged dichlor from Sams is a MUCH better idea, since it will keep much better.

On a 1600 gallon pool, a single 1lb bag of dichlor will add ~40 ppm chlorine and ~37 ppm of stabilizer. HOWEVER, with a 1600 gallon pool, you need to drain & refill every 2 weeks or so, if you are using it regularly. The dichlor will work very well with that.

If you can't buy it at Sams, here's another option at Amazon:
Nava Chemicals Quick Dissolving Chlorine Shock, Pack of 6 1-Pound Bags
Please note that, when I checked just now, NONE of the other bagged shock products on Amazon were undiluted dichlor!