newbie back. finally have new filter running. need a some guidence with test levels.

[chem geek]

How much baking soda would I need to get to a target of 80-90ppm? I used the bleach calc and it said to add 11lbs??? I can just dump it in front of the return. AG 13570 gal vynil.

Yes, I also calculate about 10 pounds which will not only bring your TA to 85 (assuming it truly is at 30 now), but will also raise your pH to about 7.1-7.2
BleachCalc is a great program and you can trust it for the calculations that it does.

However, play it safe and add about half or certainly no more than 3/4 of the amount, not all of it. Then retest your water and see where you are at. Yes, you can just dump it in front of the return. Baking soda is one of the most innocuous chemicals you will encounter. It has a slightly basic pH. If it's really powdery, it should dissolve fairly well. If it's clumpy, you might want to break it up a bit before putting it into the pool (though my experience is that it dissolves pretty well).

[EDIT]Realize that increasing pH with Borax will slightly increase your alkalinity as well (by about 5) so once you've dumped in half to 3/4 of the baking soda, start adding Borax to raise the pH to your desired level. When you're within 0.1 unit of where you want to be in pH, figure out how much more baking soda to add and you'll probably be right where you want to be.[END-EDIT]

Richard