The Beckett Replacement Pre-Filters for Beckett Filtration Pumps are designed to surround and protect a water garden pump from debris that accumulates in ponds. Depending on the size of your pond, one pad offers up to six months of effective filtration. The foam filter traps particles to prevent your pump from clogging, increasing the life of your pump. A foam filter also helps to improve water clarity by creating the perfect home for beneficial bacteria to grow. Beneficial bacteria feed on the organic material in the water that passes through the filter to keep your water clean and clear. Clean your filter regularly by submerging it into a bucket half-filled with pond water, gently massage and squeeze the foam. This ensures that the beneficial bacteria remain in the foam filter. For use with Beckett pump models DP250/DP290, DP400/DP430, FR400/FR500, FR600/FR680, FR800/FR900, LV450T, DP800/DP900.