Ultra violet filters and their uses and benefits in pond filtration.

There are a huge range of pond filtration choices available to the 21st century pond keeper all of which can help keep your fish healthy and your pond an attractive garden centre piece. The vast majority of these achieve this through a combination of physical removal of solid matter,(leaves, fish waste, uneaten food, dust etc) and the breaking down of chemical waste produced by the fish,(ammonia) through the processes of beneficial bacteria held within the filters various media. However, despite the efficiency of these filters many of us have been faced with a yearly battle with soupy green water, particularly in spring time caused by green algal blooms. This is usually the result of elevated nitrate and phosphate levels within the pond which occur naturally as a result of the filters biological process - the toxic ammonia waste of the fish being broken to similarly dangerous nitrite then finally relatively harmless nitrate which is an excellent plant food. In a well planted pond the majority of this nitrate will be used up by the vigorous plant growth typical of aquatic and bog plants, as well a regular partial water changes,(always with the addition of a suitable dechlorinator). Unfortunately in spring time these plants can often take a little while to achieve full growth rates and as a result the faster growing floating green algae’s can steal a march on their more showy relatives and multiply to plague proportions in a matter of days leading to a green pond and invisible fish! This is where the use of an ultra violet clarifier,(UV) can help grab back the advantage for your ornamental plants. These UV clarifiers work by slowing or halting the reproduction of the algae. This is achieved by the intense wavelength of UV light used being absorbed by the algae which then damages the algae’s DNA structure. This causes the algal cells to clump together and whereas previously they were small enough to flow through the mechanical stage of your bio-filter they are now large enough to become trapped and therefore removed. The benefits of this process are clear when compared to the alternatives;

No need to add chemicals to your pond with the potential associated danger of overdosing.

No adverse effects on fish, other pond life or filter bacteria.

Very low maintenance and simple to install.

Generally guarantees clear water if fitted correctly in conjunction with a suitable mechanical/bio filter and appropriate stock levels.

The only potential drawback is the need to more regularly clean the mechanical stage of your bio-filter to prevent it becoming clogged with the algae but this is surely a small price to pay for clear water and a better view of your fish?

UV filters come in a range of sizes to fit your pond and must be matched with a pump that will supply an appropriate flow rate as too fast a flow will mean the algae will not be in contact with the UV light sufficiently to cause it to clump. Many modern biological and pressurised filters come with a built in UV as standard, but if you already have a filter installed which doesn’t then they can be easily fitted retrospectively onto your system. The only maintenance usually required is a yearly replacement of the UV bulb and a clean of the quartz sleeve that exposes the ponds water to the UV light.