Installing A Lily Pond, Page 6
Pumps and Filters
Pumps are an easy subject: you need one to help circulate the water. The best advice is to get a pump that is capable of "turning the water over" once an hour. If your pond is 300 or so gallons, buy a 300 gallon per hour pump. Approximate pond sizes are always on the pump box. Pumps are usually used to pump the water through a waterfall, fountain, filter or some combination. The waterfall or fountain is key as it injects more oxygen into the pond.
Filters are a bit more involved. You can buy a sealed biological filter from the store for about $150 or you can build one for about $20. It's easy. You will need some 1/2" PVC piping, the necessary solvents to weld it, some hose clamps, silicone sealant, lava rocks, garden hose and a tub of some sort. I used a rubbermaid tub but I've also used large plastic pots (terracotta lookalikes) to do the job. The pot or tub can be installed on top of the ground and concealed or you can dig a hole and put it in the ground (but slightly above the level of the pond). If you put the tub above ground, you can build a waterfall but you will have to mound dirt around it to help conceal it. After you are finished, make sure you plant grass to hold the dirt in place. If you dig a hole for it, you can simply have the water run back into the pond. Decide which you are going to do now and place the tub.
Next, cut a notch in the container and using some dirt, build a ramp from the pond to the lip of the container. Next, using silicone sealant, attach a leftover piece of pond liner to the lip of the container. Let the pond liner run down the ramp and overhang the edge of the pond. Let the silicone cure.
Next, build a "filter element" as pictured above. The shape doesn't matter, you can build a horseshoe or square shape. It just has to fit inside of the bottom of the tub. Leave the tube sticking above the top level of the tub so you can hook the hose up to it. Next, get some lava rocks like you use in gas grill, wash them thoroughly and fill the container at least half full with them. Hook the pump up to the filter element and turn it on and check for leaks. Using small rocks, conceal the pond liner.
Now, you might experience an algae bloom in a couple of days, get a pond test kit and make sure the ph, nitrates, nitrites and other parameters are right. Most likely the algae will go away. As a last resort, you might use an algacide but this also attacks lillies and other pond plants.