Every now and then, someone takes the Pond Formulas Blueprint and runs with it — and Leslie and John from California did exactly that.
They used both the Blueprint and KevBot to plan, problem-solve, and bring their massive pool conversion to life. What they’ve created is a truly inspiring example of what can be achieved with determination, creativity, and a lot of elbow grease.
Here’s their story, in their own words 👇
The Location
Sacramento, California – Mediterranean climate with hot, dry summers and mild, somewhat wet winters.
The Project
When John and I moved to our garden-filled country property, a stagnant green swimming pool–turned–pond bloomed abundantly with pink and yellow lilies as a centerpiece.
However, as the years passed, we yearned for a clear, healthy pond with filtration and recirculation.
The Build
We converted an old stagnant swimming pool (originally 30,000 gallons) into a 6,000-gallon pond with a 1,200-gallon wetland bog filter and recirculation.
Almost everything was completed by hand — mainly the two of us, plus one part-time laborer. Friends also chipped in with time and muscle.
The old pool had been used as a pond for many years, but the water was stagnant green. The bottom was thick with about 12 inches (30 cm) of black muck and many vigorously growing water lilies.
The first step was to drain the pool, muck it out, and remove all the waterlilies.
We then poured an 8-inch-wide concrete wall to separate the bog area from the pond area. The bog wall was about 6 inches higher than the pond apron so water could flow naturally from the bog back into the pond.
The concrete wall was anchored into the pool bottom and sides with ½-inch rebar epoxied into holes drilled in the bottom and sides of the pool.
(Ask ChatGPT for some ideas on how to pour a concrete wall divider in a pool — and always review with a concrete professional who knows what they’re doing!)
Our bog area is at one end of the pool and was built to hold between 1,200 and 1,500 gallons.
(We probably could have used sandbags to build the wall instead of concrete, but we weren’t sure — so we went with concrete.)
Once the bog area was sectioned off with a concrete wall, we wanted to reduce the pool depth from nearly 6 feet to about 3½ feet.
To do this, we added ¾-inch road base to the pool and packed it with a vibrating plate compactor.
We ended up buying a compactor from Amazon, but you can rent them too.
After about 21 cubic yards of road base, the pool depth was around 4 feet.
(Note: previous owners had already filled the deep end with broken concrete up to the 6-foot depth.)
The next problem: how to create different levels (terraces) in the pool.
We decided the most flexible and adjustable way was to use sandbags.
We used sandbags to create the terraces and back-filled with more road base.
We also built an inlet bay area with sandbags.
The road base had sharp edges, so to protect the liner we covered it with construction sand and 6 oz non-woven geotextile liner before installing a 45-mil EPDM rubber liner.
Filtration System
The wetland bog filter is about 1,200–1,500 gallons.
Dimensions are irregular — approximately 12 feet by 8 feet and about 2½–3 feet deep.
Materials Used:
- Liner: 45 mil EPDM (Firestone)
- Fabric: Non-woven geotextile fabric (6 oz)
- Pump: Periha Variable PB-2500 Version 2 (32V, uses 160W at 6000 gph setting)
- Circulation Pump: Orlushy DC-12000 aquarium pump (80W, 3100 gph — probably a little undersized). We used 1-inch PVC pressure pipe (should have used 1¼”) and reduced it to ¾” for each jet placed in the corners to push water toward the inlet bay.
- Piping: 2” flexible PVC (Schedule 40)
- Pump Vaults: Gamma2 Vittles pet food containers — the square shape made it easy to cut square holes in stacked plastic pallets.
The height (about 2 feet) fit perfectly.
We used KevBot to figure out how many holes to drill for flow — horizontal slats or holes.
We found multiple 1-inch holes drilled in an offset grid gave greater stability. - Foam: Great Stuff black multipurpose foam (used on the waterfall only)
- Sandbags: Durasac heavy-duty, 14”×26”, filled by hand with construction sand.
Reservoir / Inlet Bay
- (3) 45”×56” plastic pallets (found on Craigslist)
- Overflow: scrap hose, gravity-fed to French drain
Bog Filter
- Liner: 45 mil EPDM (Firestone)
- 1 olive barrel (Craigslist)
- Bio-diffuser chamber: septic leachfield chamber at bottom of bog
- (4) 44”×56” plastic pallets (Facebook Marketplace)
- Media: 8” layers each of 3–6” cobble, 2–4” cobble, and 1½” cobble, covered with about 2” of pea gravel
- Concrete blocks were used to create a straight channel for the bio-diffuser and pickle barrel
Pond Basin
- Sandbags and road base for shape
- Liner: 45 mil EPDM (Firestone), 450 lbs — a challenge to move!
- Air Pump: Blue Diamond ET60 (60 L/hr)
- Diffusers: Matala self-weighted air hose with heavy-duty air manifold and two MD11 diffusers (9” disks)
Rocks and Stonework
Resources from local rock yards — a mix of granite and river boulders.
About 74 tons of sand, road base, gravel, cobble, boulders, and other stones were used.
Plants and Wildlife
Bog plants: calla lilies, canna lilies, bacopa, creeping jenny, and sweet flag (Acorus).
Pond plants: water hyacinth, water lilies, papyrus.
Fish: koi, goldfish, and mosquito fish — some from our previous pond and others donated by friends.
The pond and bog are full of wildlife. Birds bathe in the shallow bog stream and waterfall, dragonflies and insects are everywhere, and a garter snake has taken up residence near the water’s edge.
Although we have many predators nearby, we haven’t had any problems — probably because we have dogs.
Helpful Resources
Ozponds and KevBot were invaluable.
Although we searched high and low, we found only one example of using sandbags for pond shaping — at EarthbagBuilding.com.
Other Helpful Information:
- Auction sites: Great for tools and supplies. We bought a 36-inch mini skid steer for $2,800 — a life saver for moving boulders and sandbags.
- Tools: Rent, buy, or borrow — then resell when finished.
- Research: We spent a lot of time researching before starting. KevBot was unbelievably helpful — usually spot on.
- Electricity: Variable-speed DC pumps use far less energy (recommended by Ozponds).
- Sandbags: Easy to work with and adjust. Fill to about 45 lbs for manageability.
- Terraces: Next time, we’d make the rises shorter (12”) and runs longer (18”).
- Rocks: Some affect pH — limestone and moss rock can raise it.
- Planning: We kept a daily task and resource list. Supply chain delays were real!
- Mistakes: Things go wrong — it’s part of the learning process. Stay positive.
- Cost: About $30,000 USD total, mainly due to rock and gravel.
The build took 74 days — we’re retired, so we had the time to enjoy it.
Leslie and John
Sacramento, California
Thanks for sharing your inspiring story Leslie and John. What a transformation! If you would like to share your pond with the world use the contact page, I look forward to seeing what everyone is creating.
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