An undergravel grid (above, left) is ready for gravel. Tino’s Pond (above, right) was built by Fitz’s Fish Ponds (photo courtesy of Mike Hall). An airlift system (right) was integrated by Magnolia Ponds (photo courtesy of Max Taylor).
The farthest I have strayed from my proven design is a pond that I built 11 years ago. The homeowner wanted a pond with a completely calm surface. It was for plants primarily, but they wanted some fish, too. To meet these requirements, I designed the system with a submersible pump in a sealed box with an open pipe leading into it from half of the undergravel filter. The output from this pump went to the other half of the undergravel filter as a pressurized filter. The last thing this homeowner wanted was small gravel, and I had my doubts, but we used pea gravel. Eight years later, I talked to the homeowner, who had done zero maintenance on the system. Their only complaint was that they occasionally had to dye the water, because the pond was too clear to show off the plants as much as they wanted. I am not crazy about this system for the average homeowner, as it uses a submersible pump, which doesn’t last as long as an external pump. Moreover, this pond doesn’t have a skimmer, so the homeowner has May/June 2018
to remove surface debris manually. Most homeowners would not keep up with debris like this. You can see a picture of this pond in my previous article.
Add an Airlift It may seem hard to believe, but you can filter a large pond using 60 watts of electricity, or even less. This is another huge advantage of undergravel filtration systems. Because the filter is in the pond, it can run without having to lift water above the surface of the pond. This creates the perfect scenario to implement an airlift system. With 60 watts of power operating a good air pump, you can easily move 10,000 gallons of water through the filter. What other benefits can be expected from this kind of system? You could not have a better system for oxygenating the pond. If designed correctly, the filter should draw water from the entire bottom of the pond and bring it to the surface, where it can absorb oxygen from the air. There should be no dead areas in the bottom POND Trade Magazine 43