How do you raise cyanuric acid levels in a spa?

Cyanuric acid is generally called chlorine stabilizer and it is used to prevent the suns UV rays from eating up the chlorine in outdoor pools. Because most spa's are covered when not in use this is generally not a concern for spa or hot tub owners.

If you do however have an outdoor uncovered spa and you wish to raise the CYA level you would simply visit your local pool supply store and purchase some chlorine stabilizer, just ask for cyanuric acid and they will know what to get you.