Rubber Membrane Diffuser - 8" Long - 3/8" - 1/2" - RAD8 Ensures adequate oxygen levels during hot summer months. Maintains open water during winter months in freezing climates. An energy efficient way to aerate, de-stratify and circulate water in water gardens and koi ponds. Increased oxygen levels, which will help with decomposing organic material and result in a cleaner, healthier pond.