Valterra Pond Slide Valves Size:1.5" Inch These Bio Balls encourage bacteria These Bio Balls encourage bacteria growth with their large surface area Ballast Box Model Fits Evolution Aqua EvoUV Product Code 15w evoUV ballast electrical box UV2115CE 25w evoUV ballast electrical box UV2125CE 30w evoUV ballast electrical box UV2130CE 55w evoUV ballast electrical box UV2155CE 110w evoUV ballast electrical box UV21110CE Please ensure you select the appropriate replacement model ballast for your set up to ensure you receive the correct replacement unit Sizes Available: separating filters from the pond or other situations where you may require complete or partial water shut off