In 2018 the Washington Koi and Water Garden Society (WK&WGS) put our backyard koi pond on its pond tour. We were honored to be picked, and as usual we had a great time with the members.
Since the tour, people keep asking us two things: how we built it, and how we keep the water so crystal clear. This page answers both. Further down there's a 3D model of the pond that you can open and look around in our Pond Planner.
The pond at a glance
- Location: Bothell, Washington
- Built: summer 2016
- Shape: kidney bean, 15 by 12 feet
- Depth: 6 feet
- Volume: about 6,500 gallons total
- Waterfall: 4 to 5 feet high
- Filtration: bottom drain, skimmer, stainless steel sieve, a bead filter rated for 30,000 gallons, a polishing filter and a 200-watt UV
- Pond tour: WK&WGS, 2018
How we built it
We built the pond in the summer of 2016. Planning took about two months. Building took about three more, mostly on nights and weekends.
A composite deck with a 6-foot viewing platform wraps around half of the pond. Boulders of every shape and size cover the other half, some as heavy as 750 pounds, because we wanted that side to look like a natural shoreline. Across from the viewing platform, a big old cedar stump sits underwater with its roots spread wide. It gives the koi a natural place to hide, and it breaks up all that rock.
Apart from the koi, the falls are the focal point. They stand 4 to 5 feet high and drop mostly straight into the pond, so there's always the sound of splashing, and the water picks up plenty of oxygen on the way down. Just to the right of the falls, a small jet shoots a thin arc of water into the pond. PondMAX color-changing LED lights light up the falls and the jet at night, and that's when the pond and the koi really come alive.
Photo: Jamie Jenkins
Everything that keeps the pond running sits under the deck and around the side of the house, out of sight.
How we keep the water crystal clear
We filter it far past what the pond needs. The main filter is rated for 30,000 gallons, more than four times the pond's 6,500. Some people call that overkill. It's also why the water stays clear all year and the koi stay healthy.
It's the same advice I give customers: buy more filter than the label says you need. Filter ratings are maximums, and koi grow.
Here's what each piece does:
- Bottom drain. A 3-inch Koi Toilet I aerated bottom drain pulls waste off the floor of the pond. A PondMAX PA40 air pump feeds the drain's aerator, so the pond also gets air from the very bottom.
- Skimmer. A Savio Skimmerfilter with a 16-inch weir pulls leaves and floating debris off the surface, and its auto-fill valve tops the pond up as water evaporates. We modified the skimmer to take a 3-inch hose in the bottom.
- Sieve. A 3-inch stainless steel AquaSieve SS prefilter screens out solids before they reach the bead filter.
- Bead filter. A GC Tek AlphaONE X2 system, rated for 30,000 gallons, traps fine debris and houses the good bacteria that break down fish waste.
- Polishing filter. A PoliGlassBead XStream polishing filter, the 17,000-gallon model, catches the finest particles, the kind that leave water looking hazy.
- UV. A 200-watt UVC-6H ultraviolet clarifier kills the free-floating algae that turn pond water green.
- Pumps. Two ArtesianPro 3/4 HP High Flow pumps move the water through all of it.
- Returns. Three 1 1/2-inch tangential pond returns (TPRs) send the clean water back in at an angle, so the pond spins counterclockwise around the bottom drain. That current carries debris to the drain instead of letting it settle.
Water gardens around the yard
The koi pond isn't the only water here. We also have four smaller water gardens and fountains around the property, and most of them are planted with lotus, water lilies, iris and other water plants.
What I'd do differently
If I had to do it all over again, I'd join the WK&WGS much earlier. A club like that lets you walk through other people's ponds, see what works and ask how they built it, all before you dig your own.
Plan a pond like ours
We rebuilt our pond in the Pond Planner at its real size: the same kidney shape, 15 by 12 feet and 6 feet deep, with the deck on one side, boulder falls on the other and three returns. Here it is from above and in 3D.
Open it in the planner to look around from any angle. You don't need an account to look, and planning your own pond is free with a Play It Koi account. The planner's parts list uses equipment we sell today, so a few picks differ from what we installed in 2016.
We've rebuilt customer ponds the same way, like Leo's raised pond with viewing windows and Emerick's 20-foot round pond.
Photos of our koi and the falls
In May 2020, photographer Jamie Jenkins stopped by to buy some of our Japanese koi, and she took these photos while she was here.
