SeaChem ParaGuard ™ is a unique dialdehyde based treatment with synergistic malachite green and fish protective polymers. It is the only liquid medication on the market to control parasitic, bacterial, fungal, and viral infections. It will not damage the biological filter. It is exceptionally effective in dips. It is a highly effective and economical solution for problems of ectoparasites and infectious lesions. It will not affect the pH. A 250 mL bottle treats 500 gallons. Marine and freshwater use.