Haviland Stabilizer is fine.

Keep in mind that, on your pool, each pound of stabilizer will add 3 ppm of CYA. Also, you need to allow a week of pump RUN TIME to dissolve the CYA, if you add it via the skimmer. You might want to put in a sock in the skimmer, instead of just pouring it in. That way, it won't be lost when you clean your cartridge -- OR if it sinks to the bottom of the filter case when the pump is off, and just sits there in a pile.