BioGuard SoftSwim B (half gal) (4 Pack) BioGuard SoftSwim B is the sanitizer that contains biguanide and is step 2 in the Soft Swim program 1/2 gallon per 10,000 gallons of water to get a content of 50 ppm 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 Routine Maintenance: 1 pt per 10,000 gallons of water to raise level by 10 ppm.