Customer Corner: Billy Ngo's Low-Maintenance Koi Pond with a Wrap-Around Deck

CustomerBen Cooke
Billy Ngo pointing out his koi from the edge of his pond, with the rock waterfall and the wrap-around deck behind him

Billy Ngo told us exactly what he wanted: a "no maintenance" koi pond. No pond gets all the way there, but Billy got about as close as anyone we know. In the second video below he tells us he cleaned his pond once in an entire year.

His pond is about 9 by 13 feet and 5 feet deep. A bottom drain, a gravity-fed drum filter, a bead filter and a 300-watt UV do the work, a rocky stream cascades down the hill behind it, and a deck wraps around two sides. Here is how he planned it, the gear that runs it, and a 3D plan of his pond you can explore yourself. Skip ahead to the 3D plan.

He drew it before he dug it

Billy knew two things before he started. The pond would get a deck around it, and the hill at the back of his lot would become a stream that tumbles down it in tiers instead of a problem. He drew the whole system on paper, from the bottom drain to the sewer line, and sent it to us to check before he bought a single part.

His drawing is worth a close look. He sized the pond at about 9 by 13 feet and 5 feet deep, which he put at no more than 4,387 gallons (9 x 13 x 5 feet at 7.5 gallons per cubic foot; the real number is lower because a pond isn't a box). For the stream he budgeted 13 feet of lift and about 30 feet of pipe to the spillway at the top, and he planned on 5,000 to 7,000 gallons an hour.

Billy Ngo's pond filtration design: a 4-inch bottom drain and a skimmer gravity-feed a rotary drum filter, then the pump, bead filter and UV, with 2-inch ball valves splitting the flow between the waterfall spillway and a direct return

Here is how the water moves in his design:

  1. The 4-inch aerated bottom drain and the skimmer feed the drum filter by gravity. Each line has its own knife valve, so he can balance the pull between them.
  2. The drum screens out the solids and flushes them down a 4-inch line to the sewer, with the option to send that waste to a bucket instead.
  3. The pump pulls clean water from the drum and pushes it through the bead filter and the UV.
  4. From there the water splits. One 2-inch line climbs the hill to the spillway at the top of the stream and one comes straight back to the pond through a sidewall return, each with a 2-inch ball valve to set the balance.

Here is his sketch of the yard, then a drone shot of the finished pond. The pond, the falls, the deck and the equipment corner all ended up close to where he drew them.

Billy Ngo's pencil sketch of his backyard from above: the koi pond with a bottom drain and skimmer, the waterfall running up the slope, the stairs, the deck and the pond equipment beside the fence

Drone photo of Billy Ngo's finished koi pond: koi in dark water, a rocky stream stepping up the hill to the fence, red Japanese maples, and a brown composite deck and stairs wrapping around the pond

Billy's equipment list

This is the gear that keeps Billy's pond clear:

New to any of these? Our buyer's guides cover bottom drains, rotary drum filters, bead filters, UV clarifiers and pump sizing, and our drum filter comparison sets the PP-35 beside every other RDF model.

Twelve weeks, pond first

Once the plan was checked and the parts arrived, the build took about 12 weeks, deck included. The order mattered. The pond went in first so every rock could go exactly where Billy wanted it, and only then was the deck built and cut to the finished edge of the pond.

Billy Ngo's backyard before the pond: a lawn and a bare slope rising to the back fence beside the house's concrete steps

The dig begins, seen from the bottom of the hill: the first holes cut into the slope below the back fence

The same excavation seen from the top of the hill, looking down the slope toward the pond site and the fence line

The build came down to three stages:

  1. Excavation: dig the pond to its shape and depth, and cut the course for the waterfall into the hill.
  2. Installation: lay the geotextile underlayment and the liner, install the drain, skimmer and filtration, run the electrical safely, set the rock and finish the pond.
  3. Deck: build the wrap-around deck, structurally sound and shaped to follow the pond's edge.

Plants and koi

Around the water Billy planted a colorful mix of marginal and bog plants:

Billy keeps lots of varieties of koi, and these are his favorites:

Planning your own? Our pond plant buyer's guide covers which plants suit which depths, and our guide to koi varieties explains what sets each one apart.

Billy Ngo's koi gathered at the surface: red and white, orange, yellow and platinum koi over dark water

Koi swirling at feeding time in Billy Ngo's pond, the water rippling around them

How low is low maintenance?

Every koi pond needs some care, and "no maintenance" was always going to be a stretch. Billy's is about as close as it gets. In this video he walks us through the equipment that runs his pond, including the homemade muffler he built for his air pump. Then he hit us with a number we had never heard before: he cleaned the pond once in an entire year.

That is what this kind of system is for. The bottom drain pulls waste off the floor before it can settle, the drum filter screens it out and flushes it away on its own, and the bead filter and UV only ever see water that has already been strained. The air diffuser in the drain keeps that 5-foot-deep water moving and full of oxygen.

Plan a pond like Billy's

Now you can walk around Billy's pond yourself. We rebuilt it in our Pond Planner by tracing his drone photo and sizing the outline to the 9 by 13 feet he drew, 5 feet deep, for 3,664 gallons. A stream runs 16 feet up the hill behind it, dropping 6 feet over its tiers, with a 22-inch Aquascape spillway at the top and big boulders along both banks. More boulders sit around the edge of the pond. His Rhino II drain sits in the middle of the floor, the Helix skimmer and a straight-in sidewall return are on the fence side, and the PP-35 drum, the ArtesianPro pump, the AlphaONE 6.0 and the Matala UV line up along the fence. The deck wraps the other two sides and follows the curve of the pond, just like his.

3D view of Billy Ngo's koi pond rebuilt in the Play It Koi Pond Planner: a rocky stream cascading down the hill between boulders and red Japanese maples, the koi pond at its foot, a timber deck with Adirondack chairs wrapping around the pond, and the drum filter, pump, bead filter and UV along the fence

Close-up 3D view of the same pond in the Pond Planner: koi swimming over the aerated bottom drain, blue flag iris at the edges, boulders on the banks, the stream spilling in at the far end and the deck curving around the water

Here is Billy's drone shot next to the planner's view from straight overhead:

Side by side: Billy Ngo's drone photo of his pond, stream, deck and fence, and the same layout seen from above in the Play It Koi Pond Planner

2D plan of Billy Ngo's koi pond in the Play It Koi Pond Planner, showing the bottom drain, skimmer, sidewall return and stream, the plumbing to the equipment along the fence, the wrap-around deck, the boulders and the maples

A few things matched before we changed anything. Left to its own picks, the planner chose the same Helix skimmer, the same Rhino II aerated drain (it suggests a second one for a pond this long) and the same 300-watt Matala UV that Billy runs. For air it picked a Hakko 40L, one of the two sizes Billy says he would buy next time.

One thing is simplified: the planner lights the pond with two small warm white kits, where Billy used one kit plus a fountain and waterfall kit.

Open Billy's pond in the planner to spin it around in 3D, see where every pipe runs and check each part on the list. Like what you see? Hit "Start my own pond" and design yours. And if you would like a second pair of eyes on your plan before you buy, send it to us, just like Billy did.

Tags: Customer, Customer corner, Customer pond