BioGuard Pool Tonic - for a Stress Free Pool! BioGuard Pool Tonic The Remedy for a Sick Pool Treats up to 20,000 Gallons Salt Compatible, Phosphate Remover! Helps Prevent phosphate based scale from building up on the salt chlorinator cells, allowing salt systems to work at their optimal level Pool Tonic Removes Rain Pollution, Pollen, Dirt, Dust, Skin Oils, Greases, Lotions, Hair Gel, Hair Spray and Pet Dander