HOW TO USE THE FLUID For normal cases, use 10 to 12 ounces of Rigid per gallon of diluted fluid. On difficult cases or extended stay cases, we recommend using at least 16 or more ounces per gallon of diluted fluid. In hard water areas, use 2 to 4 ounces per gallon of Water/Clot Guard. Also use Water/Clot Guard when moderate to heavy clotting is anticipated or distribution seems to be poor.