If you have access to a Sams Club, I'd buy 2 of their 24# boxes of bagged dichlor. Each 1lb bag will add about 2.5 ppm of chlorine, and 2 ppm of stabilizer (CYA). Once you've reached 60 ppm CYA (= ~30 bags of dichlor, on your pool), you'll want to switch to bleach. Dichlor ALSO lowers your pH, not immediately, but later. So, you'll need some of the borax on hand, to maintain your pH, but since your pH is starting a bit high, you may not need it aft first.

You can also use cal hypo, cautiously. It will add calcium which you will need at first.

However, you need to understand that with a pool in the desert, and with a DE filter, you are going to be constantly losing water to evaporation -- leaving all the minerals behind. And with a DE filter, you will NOT be losing water to backwashing. This means the replace water will ADD to the calcium present.

So, while you want to get your calcium up some now (maybe, 180) you don't want to hurry, and you don't want to go too far, since you'll also be adding MORE calcium every time you top off your water.