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Ultra Violet Light Destroys Algae In Garden Fish Ponds ... Guaranteed

In instances of high and sunlight, warm weather and fish nutrients and if we did not have Ultra Violet on our side we would not see much of our fish in most garden ponds. You see; warmth and sunlight mixed with nutrients emanating from fish secretions and food excesses create perfect conditions for algae to grow no matter what kind of biofilter we have and no matter how good it is.

These normally green plants replicating at the rate of 30 times per hour under ideal conditions can quickly give a pond a pea-soup appearance. This pea soup needs to be seriously avoided if we want clean and clear water.

Persistently green water can easily lead to fish deaths from oxygen starvation and ammonia poisoning.

What is Ultra Violet light?

Technically it is a source of light enjoying a particular wavelength and it appears to be blue. What is important to us is not what it looks like so much as what it can do for us. Equally important is what it does. Here's the summary:

  1. Ultra Violet Light Clarification Will NOT kill any algae not exposed directly to the UV rays - ie those algae not circulating in the pond water because they are not exposed directly to the UV rays eg blanket weed, or algae attached to pond surfaces

  2. Ultra Violet Light Clarification Will NOT kill bacteria or viruses. The design is such that pond units cannot reach sufficiently high radiation levels. Sterilisation UV units are required for this purpose.

  3. Ultra Violet Light Clarification Will NOT harm plants, fish or filter bacteria

Ultra violet light or an UVC will provide clear water when designed and installed correctly without any doubt so long as murkiness is due to algae presence

Performance of an Ultra Violet Clarifier

  • Choose the correct wattage. The unit must be correctly sized to take into consideration stocking density, sunlight exposure and water volume.

  • The unit must have a quartz tube installed. This tube insulates the UV lamp from the water thereby allowing the optimum lamp burn temperature of 40 degrees Centigrade to be achieved.

  • Flow rate should not exceed the manufacturers suggested range.

  • The quartz tube should be kept clean since dirt on the surface inhibits the radiation from UV light.

  • The lamp MUST be replaced annually at least since it ceases to operate after about 8000 hours of active life. It is best to leave the UV on 24 hrs per day but not essential like the biofilter.

How does the UV work?

When algae are exposed to UV light the cell wall is destroyed. The result of this is that algae clump together. Prior to clumping a single algae cell has a diameter of about 4 microns (4 millionths of a metre or very very small). Because algae are so small it is difficult for any filter to remove it. However after clumping the filter can do a good job of mechanically removing the algae.

The UV lamp does not prevent algae forming. It works by killing the algae faster than they can make the water go green. The algae will still tend to form so long as the conditions suit them. However if the wattage of the UV clarifier is too low then the water will remain green for the reason that the algae are forming more quickly than they can be killed. If in any doubt when choosing an UV clarifier go for a larger size. You cannot overdose with UV!

If you install an UV in a pond whose water is already green then it will take some days to clear depending on wattage of the unit. Also be aware that the quartz tube may well get fouled up with green algae seriously reducing the radiation. If the pond has not cleared inside a week then check the quartz tube and clean it if necessary. Repeat also if necessary. Your pond will go clear unless the wattage is insufficient - promise.

The use of an UV Clarifier in my opinion is absolutely mandatory to be able to enjoy a pond to its maximum and also safeguard fish in that pond from aggressive algae blooms potentially causing fish mortalities. The use of an UV is one of the very best things to happen to pond keeping and has contributed enormously to the growth in successful and enjoyable pond keeping all over the world.

By the way do not let anyone tell you an UV will damage your filter's performance. This is nonsense. Also pond UV's cannot kill bacteria or viruses as some people claim.

UV will certainly kill bacteria and viruses but not as designed into a pond UV Clarifier. Aquarium units are often designed to control bacteria they are then called UV Sterilisers, and not UV Clarifiers. There is a big difference. Breweries and pharmaceutical companies etc use UV sterilisation but the equipment is very expensive and has to be totally reliable.

A final word. If you have not got this blue-light miracle worker then do go out and buy one. You wont regret it.


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