Nutrafin Phosphate Reagent No.3 Refill for Aquarium, 10ml Phosphate reagent #3 refill is for use with nutrafin's phosphate (0.0-1.0 mg/l) test kit Phosphate levels should be monitored weekly High levels of phosphate, often the result of overfeeding or infrequent water changes, can contribute to unsightly algae growth Measures 1-inch length by 1-inch width by 3-inch height Comes in 10-milliliter refill pack