That's a lot of CYA! But, it will keep from one season to the next. For reference, in a 30K gallon pool, it will take approximately 2-1/2 lbs to add 10ppm of CYA. Go slow with adding it so you don't overshoot your target.

You can add it a couple of ways.
1) Add it slowly to the skimmer while the pump is running and then keep your pump running 24/7 for the next 4-5 days and don't backwash or retest CYA for a week to make sure it is all dissolved.
2) Put it in an old sock and hang it in front of a return jet. Give the sock a squeeze every now and then to help it dissolve faster. Again, don't retest CYA for about a week.

Better to give it time so you can be sure it is all dissolved and registering on your test before deciding to add more.