Pond Tips – Pond Filtration
A few tips concerning the complicated subject of pond filtration.
The greater majority of the ponds, pools and water features that Water Gems build, require no filtration at all. The best way to keep water clear and oxygenated, is to plant the pond heavily with submerged plants and not to overstock it with fish.
The plants absorb any free nutrients and light, leaving none for the algae. This prevents the algae growing into unsightly mats, or making the water green. There is also no need to move water with pumps, as long as there isn’t a lot of organic matter in the pool, causing an oxygen deficit. Often the worst cases of filamentous algae have been where a big pump is running a cascade or waterfall.
If planted up properly, an ordinary garden pond with goldfish, has no need of a pump or filtration. Filtration is only necessary if you have more fish than the pool can cope with.
Common Filtration Methods
A standard box filter will help by trapping suspended solids. Also, an Ultra Violet clarifier mounted on the filter lid, will break up phytoplankton and keep the water clear. However, with this the nutrients are still dissolved in the water. Sometimes this causes a problem where you swap green water for clear water, smothered in filamentous algae. All things considered, planting up informal garden ponds properly, is a far better solution rather than the need for filtration.
Cases that usually do need some type of filtration, are shallow cascades or rills, and formal pools or fountains. These are water features where plants will tend to get in the way of a contemporary or formal design. Here you may well need to combine several methods to guarantee clear water, free from algae. A combination of filtration to trap suspended particles, a UV clarifier to kill phytoplankton. and a dosing system to clear filamentous algae will work well.
Filtration systems can be costly to install. They also need to be well maintained in the future, in order to keep them working efficiently. Many of the formal fountains that you see in public places have these systems hidden away below ground, in plant rooms that cost tens of thousands of pounds. Not really what you want in your back garden!
A good filtration unit for a fish pond with a medium stocking density of fish – a vortex filter for solids, a bead filter mainly for biological filtration and a UV unit.