BioGuard SoftSwim B is the sanitizer that contains biguanide and is step 2 in the Soft Swim program. This step kills and controls harmful bacteria and is gentle on eyes, hair, and skin. SoftSwim B is UV-shielded and is resistant to evaporating in the sun. The SoftSwim program is ideal for in-ground or above-ground pools containing less than 25,000 gallons of water, pools that have bottom drains, and pools that have excellent circulation with the pump operating at least 12 hours per day. SoftSwim sanitizes with biguanide.