This is a review of the Pondmaster 20-watt UV filter. The pond is 300 gallons and 20 watts is overkill. A 10 watt would work fine. The filter works really good.
Check it out at: http://www.thepondguy.com/category/water-gardens-fish-ponds-pressurized-filters A great option for existing ponds up to 4,800 gallons. The UV light filtration eliminates discolored water, while the media pads and bioballs provides both mechanical and biological filtration to remove large debris and dissolve organics. The AllClear™ G1 and AllClear™ PLUS G1 Pressurized Filters provides a 3-in-1 solution to keep your pond water healthy, balanced and crystal clear.