Construction - Plan Twice, Dig Once

CONSTRUCTION
Before you begin construction, ask yourself what you want from your pond. Will it be purely decorative, or filled with plants and fish? Our Design Thoughts article can help guide you through these early steps. Once you have determined the purpose, shape, depth and location of your new pond, your installer can start digging. Well, almost…


Planning
It’s a good idea to lay out string or garden hose in the proposed shape of your pond. Before digging, place the skimmer and waterfall boxes on the ground, at opposite ends of the pond, to make sure you’ll have good flow across the pond, and look for sharp corners or “dead zones” that can trap debris. Keep in mind that decorative rocks in the pond will take up quite a bit of space, so double check that your perimeter is big enough. We also recommend making your pond as large as your space and budget will allow. Oddly enough, larger ponds are more stable and are easier on your fish and plants, as the water temperature, PH, and other chemicals will not fluctuate as much as they do in a small pond.

Digging
As dirt is coming out of the ground, much of it can be used to build up a low, wide berm around the pond (if you're building a natural-style pond). The berm will prevent any runoff from the lawn, such as fertilizers or other chemicals, from fouling the water. It also creates a nice transition for the pond and keeps your waterfall from looking like a random pile of rocks in the middle of a flat yard. The hole for the skimmer should be dug and the skimmer placed to establish the water level. Your installer should check the sides frequently for low (or high) spots, and to make sure the any shelves inside the pond are deep enough and wide enough to hold rocks and plants (if desired). Plumbing around the outside of the pond will connect the skimmer, external pump, filter and waterfall; another set will connect the skimmer to an overflow pipe to carry rainwater away and prevent flooding. If you have a bog, there will be a third connection between it, the skimmer and the pump.


Placing the Liner
Once the hole is dug, it should be checked carefully for tree roots, construction debris or sharp rocks. Especially in rocky soil, it’s a good idea to put down a couple of inches of sand to help protect the liner. A commercial underlayment made of strong, durable synthetic material should be placed next. Note: we’ve repaired many leaky ponds that utilized old carpet, carpet pads and even a thick layer of newspaper for underlayment. Over time these materials rotted away and failed to protect the liner from a sharp rock or other material. Remember, the liner is subjected to thousands of pounds of pressure and even a small rock can eventually wear through it.

When placing the liner, excess material should be neatly folded. These folds should be placed opposite the direction of water flow, so the water passes smoothly over the fold and does not push debris into it. Outside of the pond, we like to create a very low berm under the edges of the excess liner, so it is tapered down and away. Folding the liner under may work in a dry climate, but here in the NW folded liner can channel rainwater underneath and turn the soil near the pond to mud. This loose, wet dirt won’t be able to support the combined weight of water and rocks and will likely fail over time. (See David’s pond.)

The Bottom of the Pond
To keep your pond healthy, you will need to be able to clean fish waste, plant material and uneaten food off the bottom of the pond. Some pond enthusiasts swear by bottom drains that pull water down through the liner, into a filter and then on to the pump. While this may work well in areas with very stable ground or mild climates, we don’t recommend it with loose, rocky, or wet soil. Eventually, shifting soil under the pond can cause that junction to leak. We’ve had great luck with a grid of PVC pipe, drilled along the top and sides every couple of inches. The plumbing is valved to allow water to be pulled into the grid or pushed up to flush the pond bottom. A layer of round rock covers the pipe from view and provides a smooth floor to the pond. (A definite plus when you’re trying to net a fish!)

Rocks
Like most rookie pond builders, our first pond was completely lined with rocks. Sure it looked nice, but those rocks displaced a whole lot of water, and the fish waste and debris that filtered down into all those gaps made maintenance pretty difficult. Now we put a ledge between 12” – 15” deep and about 12” wide (with pockets here and there for plants). This allows us to build a wall of rocks up the side of the pond, hiding the liner and allowing a nice edge transition. We like to vary the size, shape and color of edge rocks for a more natural look, and will pull a few out into the landscaping to tie the pond into the rest of the yard.

Now that the basic installation is done, it’s time to treat the water with dechlorinator and bacteria to get the biological system going. Add plants as soon as possible, test the water frequently until the PH and other chemicals level out, then start slowly adding fish.