Hi, and welcome to the forum!!
I'm assuming the stabilizer that you have is granular. If so, and you have a 25K gallon pool, 67 ounces of it should get your pool to 20 ppm of CYA. You can either add it through the skimmer and let it dissolve in the filter (don't backwash for several days or you'll wash it out and have to start over) or put it in an old sock and tie it in front of a return and let it dissolve that way. Either way, it will take 4-6 days before you have stabilizer in the water to help preserve your chlorine. If you plan to use tabs, you can use them at the same time, because they will also raise your CYA, although slowly--just check the ingredient label first and make sure they don't contain copper. If they do, take them back and exchange them for something else (liquid chlorine, maybe?). Most folks run a CYA of 40-50 in their pools, so you can probably use the tabs for the rest of the summer with no problem. Just be aware that as your CYA level rises, so must your baseline chlorine levels. See the "best guess table" linked in my sig for more information there.
Stay away from the Pristine Blue. You don't need it. see if you can swap it for something useable, like a float (or maybe liquid chlorine???)
You need to keep your chlorine, for now, between 3-6 ppm at all times. In a pool of 25K gallons, each 3.5 quarts of 6% bleach will raise your chlorine by 2 ppm. Until you have CYA in the water, the sun will deplete it quickly, so you really need to test and add more at least 2-3 times a day so it never gets to zero. You DO need a good test kit, but for now, if you can pick up the 6-way drop based kit at WalMart for $20, it will help you get by until you can get a better kit. At the very least, get the cheap OTO (red and yellow drops that measure CL and pH) to use for now. After your stabilizer is in the water, then you'll need to up the chlorine a little but won't have to add it so many times in a day.
Test your pH, and keep it between 7.0 and 7.8--use 20-mule team borax to raise it, and muriatic or dry acid to lower. Test your alk--in your pool, anything between 60-140 is going to be fine. If you have to raise it, use baking soda. To lower it is a whole different thread.....
To use the pool calculator, add your gallons in the window, go to the parameter that you're trying to change, and enter the "now" and "target" values. Then go back to the top and hit "calculate".
Hope this helps, and we're open to most any question you have!!
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