BioGuard Stabilizer 100 | Chlorine Stabilizer

BioGuard Stabilizer 100 is 100% cyanuric acid — sunscreen for your chlorine. It's a fully soluble granular product that prevents free chlorine from being destroyed by sunlight, and on an outdoor pool it's the difference between chlorine that lasts and chlorine that's gone by dinnertime. Ultraviolet light is the single largest drain on chlorine in an outdoor pool. Unprotected free chlorine breaks down rapidly in direct sun — a pool with no stabilizer can lose a substantial share of its residual in a matter of hours on a bright summer day. That's chlorine you paid for, doing nothing but absorbing UV. The pool then reads low, the owner adds more, and the cycle repeats every afternoon. Cyanuric acid stops that. It bonds loosely with free chlorine and shields it from ultraviolet degradation, then releases it as the chlorine is consumed doing actual work. The residual survives the day, and chlorine consumption and maintenance costs both drop measurably. It also improves the efficiency of chlorine generators, which is why salt pool owners care about it as much as tablet users do. The catch, and it's an important one: cyanuric acid accumulates permanently. It doesn't evaporate, doesn't break down, doesn't burn off, and doesn't filter out. Every dose stays until you dilute it. And if you feed chlorine with trichlor tablets, dichlor granules, or a dichlor-based shock, you're already adding stabilizer with every application — those products are built on a cyanurate backbone. That makes this a product to buy deliberately, based on a test reading, rather than as routine maintenance. Get it right and your chlorine stretches much further. Overshoot and you create the opposite problem: a pool that tests fine and behaves like it has no sanitizer at all. Pro Tip: Test cyanuric acid before you buy this, and don't add it at all if you feed with trichlor or dichlor. Tablets, sticks, granular dichlor sanitizer, and dichlor-based shock all contribute cyanuric acid every time you use them — a pool on tablets typically reaches its target stabilizer level on its own within weeks and keeps climbing from there. Adding Stabilizer 100 on top of that is how pools end up locked up in August. This product is for pools starting from a fresh fill, pools using unstabilized chlorine like cal hypo or liquid, and salt generator pools. If you're on tablets, test first and you'll likely find you need none. Brand BioGuard®