Natural ponds that aren’t used for swimming can be planted as heavily or lightly as you like. However, swimming ponds need a specific amount of planted and clear areas. Too much planting results in clean water but doesn’t leave you with enough space for enjoying your swimming pond. Putting in too few plants results in cloudy water that isn’t clean enough for safe swimming. Each pond has a specific ratio that is perfect for its volume and shape. However, a general 50/50 ratio is a good set of guidelines to start your natural swimming pond design.
Half Plants, Half Swimming Area
Dedicating 50% of the surface area to plants and 50% to open swimming area will work for most open designs. This ratio is recommended for both combined pond designs where the plants are mixed into the swimming area and separated layouts with a restoration zone separate from the rest of the pond. This ratio works for both small and large natural swimming ponds relying on planted water filtration zones. If a powered filtration system or skimmers are added to the design, the plant to swimming area ratio is usually reduced to leave more space open for splashing around.
Adjusting the Ratio
If you’re going to use the swimming pond heavily or need to accommodate more than two or three people at a time, you may need to add a higher ratio of planted area to open swimming zone. This helps the pond process extra oils and residues released by your skin into the water, in addition to residue tracked into the pond. Ponds with high levels of traffic may need a ratio of 60% or 70% planted surface area to swimming area. In order to leave enough space for comfortable swimming, these high ratio systems often reach multiple acres in total surface area.
Separate or Mixed Planting
You’ll need the same amount of total surface area covered by plants whether you separate them in a secondary pond or mix them into the swimming area. However, it’s harder to measure square footage in a mixed planting situation than with a separate processing section. If you’re mixing the plants along the edges of the swimming area, add at least an extra 10% of surface area to ensure you’re getting enough filtration action to keep the water clean.
Filtration Additions
It’s not necessary to use powered filtration methods when designing a natural swimming pond. Yet some pond owners prefer a hybrid design that still includes at least some amount of electric skimming and filtration to treat the water. If filters are added to the pond that process at least 50% to 75% of the total water volume, the planted area can be reduced to as little as 20% of the total pond surface area. Unfortunately, this hybrid approach adds to the annual cost and requires much more maintenance than just relying on a higher ratio of plants to swimming area. Stick to a 50/50 ratio, or more, to reduce the need for costly filters.
