Homemade Natural Pond Filter
In order to keep a small swimming pond clean, we created a natural filter that uses a 12V solar-powered pump and a log-framed “tub” with layers of gravel and sand.
Materials
Submersible Pump for pulling the water from the swimming pond into the filtration tub
12V Solar Panel to power the pump
Logs to line outside of the tub
Timberlok Screws to secure the logs together
Bricks/Stones to elevate the logs off the ground
Corrugated Tubing to lie underneath the gravel
Cap for Corrugated Tubing
Thick Mat/Fabric to go underneath the tarp
Plastic tarp to contain the water
Porous fabric material to go in between layers of gravel and sand
Water plants to consume what comes from the pond and clean water
Fish are a good idea to prevent mosquito larvae but if frogs are nearby, tadpoles may do the same
Tools
Level, Driver, Drill or another to poke holes in tubing, Hand Saw or Ax to shape logs, Hose
Instructions
We are using a 12V DC submersible pump to bring water from the swimming pond into the filtration tub. We are powering the pump using a 12V solar panel that is placed in a sunny spot nearby.
We started the build by cutting down trees, debarked them (to reduce rotting), and arranging them for the shape that we wanted our filtration tub to be. The inside of our tub is ~72" by 62".We used a level to make sure that the lowest point was where we wanted the water to drain. We then screwed the logs together.
Next, we laid down an old sail (not shown) underneath where the tarp will be. This is to prevent the tarp from being punctured by anything on the ground. Note: if you use some waterproof material that is thicker (like a sheet of EPDM) you won’t have to worry about this. We made sure that the tarp had enough slack that it would not be tight or suspended when filled with water.
We poked holes in the corrugated tubing in order for the water to flow out evenly underneath the sand, rather than in one place. This distribution is very essential for good filtration. We added a cap onto the end of the tube, for obvious reasons. After laying a layer of thin porous fabric to prevent the gravel from breaking the plastic, we then snaked the tube along the bottom of the tub. The tube will enter the tub from the direction of the pond (left-hand side of photo below) and will connect to the output of the submersible pump.
We added a layer of gravel surrounding the tube. We didn’t have that much gravel so we focused on the area around the tubing. Next, we laid another layer of the thin fabric over the gravel before pouring sand over it. This is to prevent the sand from getting into the corrugated tubing through the holes.
When we turned on the pump, very silty water began to come up and we let this drain slowly over a few hours before directing the water into the swimming pond. Silty water is very conducive to algae growth.
Once the water became clean and clear, we added water plants to it.
Dissolved nutrients, such as nitrogen or phosphorus, chemically bond with some types of soil particles. They are then taken up by plants, thus removing them from the soil before they can enter an aquifer.
The far left side of the picture above is where the water will flow from the tub into the swimming pond.
The final step is to add fish to eat the pesky mosquitoes that breed in stagnant water.
