The health of your backyard pond can be impacted by any number of outside forces, including excessive heat -- which can cause oxygen shortage -- fish-hungry eagles and herons, and debris from surrounding plants. You can address these problems with various types of screening, from self-sustaining measures like water plants to fine mesh that keeps mosquitoes from breeding in your pond. Commercially manufactured screens range in price from $100 to cover a very small pond to thousands of dollars for a large one. One way to save money is to drape the appropriate screening over a homemade frame of PVC pipe.
Measure the length and width at the longest and widest points of your pond, or the portion of it that you need to cover. For instance, if you have a particularly large pond with a shallow end that is vulnerable to predators or solar gain, you might want to confine your screening to the shallow area and save money by leaving the other part open.
Plan your project on paper so you can put together an accurate parts list. Start with a square base using the length and width you measured. You can plan a square, house-like frame suitable for a tallish structure intended to resist predators, or a Quonset hut-style arch made by bowing PVC members from one side to the other. The latter structure is more suitable for wider applications where the square structure might tend to sag in the middle. In general, you'll want to use 1-inch PVC -- or larger if the structure is a big one -- for the base, and smaller diameters for the upper part if you are doing an arched roof. Draw vertical members no more than 36 inches apart -- less is fine -- and note a fitting type for each corner or joint.
Take your list and your drawing with you when you shop for parts because you might need to make adjustments based on available materials. This is also an opportunity to get suggestions from the store's on-site expert, if any. Look for UV-resistant PVC, but if you can't find it, plan on painting the finished structure with water-based latex paint to block the sun's rays. Consider asking about clear PVC. It is priced a tad higher than conventional PVC, but the transparent variety offers aesthetic possibilities that other PVC does not.
Lay out your PVC pieces in a flat area and cut the horizontal base members into sections of 36 inches, or less if needed, to make a symmetrical design. A hacksaw works nicely for cutting PVC. Cut ceiling members for an arched roof longer than the width of the base by at least 25 percent. The cross members for a flat roof will be the width of the base connected via elbows, or corner fittings, to small pieces of whatever height you want the screen to stand.
Assemble the base of the structure, rejoining the cut-apart pieces of each straight section with a three-way fitting. Ensure that the third leg of each three-way is pointed in exactly the same direction perpendicular to the horizontal member. When you assemble the corners of the "flat-roof" structure, secure each piece with the open legs of the three-way fittings pointed straight up. If you are planning an arched structure, point the legs of the three-way fitting inward at about a 90-degree angle.
Fit the ends of the upper pieces into the legs of the three-way fittings and assemble from there. Fit one end of each archway piece into an open three-way leg and bend it gently until you can fit it into the corresponding leg on the other side.
Glue the parts together when it is clear that everything is going to fit correctly. Pull the dry-fitted pieces apart, smear the glue in an unbroken line around the inside of the outside pieces and the outside of the inside pieces, and push them together. Work quickly and do only one joint at a time, as the glue has a short drying time.
Drape the structure in shade cloth to cut the amount of sunlight that hits the water. This will keep the water temperature down and oxygen level up. Shade cloth comes in varying densities, so you can precisely tailor the amount of light you want to allow through. Shade cloth is also sturdy enough to repel most birds who might be hunting fish in your pond. Secure shade cloth to the bottom of the frame by either sewing it or by using special fasteners offered by shade cloth retailers. Shade cloth will also keep debris and larger insects out of the pond.
Wrap the structure in chicken wire or hardware cloth to keep predator birds, raccoons and other large pests away from your fish. This material will also keep small children from falling in or the neighbors' dogs from taking a dip. Secure wire to the base members by wrapping it under the edge and twisting smaller wires through the outside and inside layers.
Stretch window screening material over the frame to prevent mosquitoes from accessing your pond to lay eggs. Window screening comes in both metal and nylon forms and can be obtained in various colors. Wrap it under the edge of the frame and secure it with grommets or by "sewing" it in place with metal wire. Stretch it as tightly as you can without tearing it.
- Fill the bottom horizontal PVC members with water before sealing them to add bottom weight and improve stability.
Billie Jo Jannen is a politics and lifestyle columnist in rural San Diego County and a senior copy editor for Demand Media. Her writing and editing career spans 23 years, and she specializes in border and environmental affairs. Jannen's eclectic education includes engineering and horticulture, and she represents the Rural Economic Action League in regional economic development planning.