BioGuard SoftSwim B is the sanitizer at the center of the SoftSwim program — Step B, and the product that actually does the disinfecting. It’s a 20% polyhexamethylene biguanide solution, and it’s the reason a SoftSwim pool contains no chlorine at all.
Biguanide is a genuinely different class of sanitizer, not a milder version of chlorine. It kills and controls harmful bacteria through a completely separate mechanism, and the practical differences show up immediately. There’s no chlorine smell. Nothing stings eyes or dries out skin. Swimsuits and hair aren’t bleached. And because biguanide isn’t an oxidizer, it’s non-corrosive — it doesn’t attack equipment, fittings, or pool surfaces the way an aggressive chlorine residual can.
It’s also considerably more stable than chlorine. Biguanide is UV-shielded and won’t evaporate in sunlight, so it doesn’t burn off through a hot afternoon the way unstabilized chlorine does, and it needs no cyanuric acid to protect it — which means no stabilizer accumulating in the pool year after year. It’s effective across a wide pH range rather than losing most of its punch above 7.8, and it doesn’t push pH around itself. Fewer variables to chase, fewer corrections through a season.
The formula also has a polymeric action that attracts contaminants, gathering suspended material into larger masses the filter can capture. That’s part of why SoftSwim pools tend to look notably clear when the program is maintained properly.
The number to know is 50 ppm. That’s the target concentration, and it’s an order of magnitude different from the 1–4 ppm a chlorine pool runs. A standard chlorine test kit will read essentially nothing in a SoftSwim pool — this program requires its own test strips, and there’s no working around that.
Pro Tip: Learn the two numbers that matter and never let the second one slip. Target concentration is 50 ppm, and the level should never be allowed to drop below 30 ppm. That floor is not a suggestion — below it, the pool is under-sanitized regardless of how clear the water looks, and biguanide gives you far less visual warning than chlorine does. A pint per 10,000 gallons raises the level about 10 ppm, so a top-up is a small, cheap correction if you catch it on a weekly test. Waiting until the water looks wrong means you’re already well past the point where a top-up would have fixed it.
Brand
BioGuard®
