The DHP Series pumps include an impeller design that allows it to resist blockage and send debris up to 3/8' to an external filter for removal. - http://www.petco.com/product/112404/TetraPond-DHP-Pond
A beautiful, natural looking water garden will be a focal point in your home landscape for years to come. Seamlessly blending the pond into your yard is the goal. And using the right equipment is the key. Tetra offers several systems to filter the pond, create dynamic water movement through waterfalls and fountains, and enhance the beauty of the pond and its surroundings. Here are some considerations to keep in mind as you make your choices. Every pond needs a pump to keep it clean. And you need to choose the right size pump for your water garden. Make sure the pump you choose can recirculate the entire water volume at least once an hour. There is no such thing as over circulation, so it's perfectly fine to use a slightly more powerful pump than is required. In addition, extra pump power will come in handy should you decide to add onto your pond in the future. For features like waterfalls, streams, and fountains, there are additional factors to consider. The maximum waterfall is at the pond surface. Pumping the water above the surface will reduce the flow. Head height is the term for that point where a pump becomes incapable of producing flow. The pump you choose needs to be powerful enough to move the water through the feature at a desired height. All Tetra pump packages include information about flow rates at various heights. Match the pump capabilities with your pond's features, and you'll have the right pump for the job. Keep this fact in mind. The width of your waterfall is determined by the volume of water flowing. Every 100 gallons of water per hour at the discharge point creates about an inch of waterfall width. In the case of this waterfall, the pump discharge is approximately two feet above the water's surface, and the pumps capacity is 550 gallons per hour. Watch the change in effect as you increase the water flow. So choose the pump that can deliver the flow you need for the effect you want. For hassle free, clog free performance, use one of the Tetra debris handling pumps. This rugged pump can handle debris up to one fourth inch without clogging. Tetra debris handling pumps are ideal for powering external filters and waterfalls. And remember, all Tetra water garden pumps are for submersible use only, and should always operate under water.