Sunny,
Why do you want to raise your alkalinity? The typically recommended range is 80-125. Some people do say that you CAN go quite a bit higher with a vinyl pool but there's not really any need to unless you're having difficulty controlling your pH.

Your pH on the other hand is probably at least 8.2 and could be considerably higher. Most test kits only measure up to 8.2 (or less) and anything higher will look pretty much like 8.2 on the color comparator.