Do you suffer from green pond water, caused by algae blooms? If so then I am willing to bet that you do not have a UV sterilizer or UV clarifier installed in your pond? You do! OK then have you changed the UV bulbs recently?
Without a shadow of a doubt a UV light is essential for all garden ponds where there is metabolic activity taking place. Pond algae blooms are caused by microscopic algae cells (up to 4 microns in diameter) that feed on Nitrates in the pond water. They are particularly prevalent in warm weather conditions, when there is plenty of sunlight.
A small amount of green pond algae is beneficial to aquatic pond life such as Koi and goldfish; they use it as a food source and as a camouflage from herons, king fishers and other predatory birds. Algae blooms also act as a sun shade on hot summer days.
Unfortunately pond algae multiplies at a phenomenal rate and if left untreated will eventually ruin the look of your pond and will start to interfere with the pond pH and levels of oxygen in the pond. Remember that oxygen is vital to the effective oxidization of ammonia into nitrites and then into nitrates by the nitrifying bacteria colonies, housed in your pond biofilter.
The most effective way to control pond algae is to use a UV sterilizer, also known as a UV clarifier, UV light or simply a UV. Some people prefer to use pond algaecide products but if I were you I would not; they interfere with the water quality, may cause fish fatalities if overdosed and may interfere with nitrifying bacteria.
A UV Pond Sterilizer Is Affected By Temperature
The power of blue ultraviolet light that is generated at a particular wavelength is a miracle for pond keepers. UV light occurs naturally in nature and is one of the reasons we get sunburned on holiday.
The effectiveness of a UV sterilizer is affected by temperature to a large extent. At 40 C (104 F) it works at maximum efficiency. A drop in temperature to 20 C (68 F) results in a drop in efficiency to only 50%. If the unit is placed inside the pond then it will work at what ever the water temperature is.
The way manufacturers get around the drop in efficiency is to use a quartz sleeve, which insulates the lamp against cold water temperatures, ensuring maximum efficiency is maintained. Ultraviolet light transmits easily through quartz, but not glass. For this reason quartz sleeves are used instead of glass in the manufacture of UV clarifiers. Beware that not all manufacturers use a quartz sleeve; some use plastic sleeves. Look at the production specification and if it does not have a quartz sleeve, move on!
How Does A UV Sterilizer Work In A Fish Pond?
Pond water is pumped through a quartz tube, preventing cold pond water from coming into contact with the ultraviolet light source. Remember that UV effectiveness is affected by temperature and works optimally at 40C. As the water flows through the sleeve it is bombarded by ultra violet rays, either directly or via highly reflective metal surfaces.
The ultra violet light kills the microscopic algae by destroying the cell walls, causing what is known as flocculation to occur (the dead algae clump together forming a much large mass). This mass is now too big to pass through the mechanical filtration systems employed by your pond filter and is trapped and removed from the pond water.
Other Methods Used To Control Pond Algae
* Pond Algaecides are not in my opinion a good idea for the following reasons: they need to be administered in precise doses; too much can harm nitrifying bacteria colonies and the health of pond fish. They only work for a short period of time. In the long term they will prove to be more costly than buying a UV clarifier in the first place.
* Veggie filters consist of pond plants that are deliberately starved of nutrients. The aquatic plants get their food source from the nitrates in the pond water. They compete with algae for these nutrients and as a result help to keep the pond algae under control. They do not guarantee algae free ponds however.
The only guaranteed way of controlling green pond algae is to use a UV sterilizer. Many modern pond filters incorporate a UV into their design. This means that you have the money saving advantage of biological pond filtration and UV clarification from a single piece of pond keeping equipment. Another advantage of a combined UV pond filter is that the filter and UV have been designed to work together. You do not have to worry about incompatibility issues.
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