The Benefits of Using an Ultraviolet (UV) Light

UV lights are a common alternative to using chemicals to disinfect and rid your pond water of green algae. Saving you time and money in the long run and keeping it simple. Killing Algae with a UV is safe, not harmful to the fish or eco system and consistently maintains water clarity year round.

How a UV Light works

Only the water that passes through the UV chamber will be treated. Inside the chamber is a quartz sleeve that contains and protects a UV lamp from shorting out because of the power cord connected to the UV lamp. When water passes over the quartz sleeve, the UV light transmits a specific light spectrum that damages the Algae and possible protozoan's within the water. Protozoan sterilization requires a slower flow rate then Algae. If the Algae receives enough damage from the UV light, it fails to be able to reproduce or live. Dead algae may be trapped in filters and/or consumed by beneficial bacteria. The key to successfully killing either Algae or Protozoan's is flow rates.

The Anatomy of a UV Light diagram

UV light chambers can be made from different materials. Usually plastic or Stainless steel. Shown below is a cut-a-way diagram of Emperor Aquatics 50 Watt UV and a simple cut-a-way of a AQUA Classic UV to help understand what's inside and the different parts.

Click the Images to Expand
uv light anatomy diagram of a uv lightuv light anatomy diagram of a uv light

UV Lamp Light Warning!

IMPORTANT: DO NOT LOOK DIRECTLY AT A UV LAMP WHEN IT IS ON! It can be harmful to your eyes....

Replacement of the UV lamp
Each manufacturer specifies the approximate length of time to replace the UV lamp. This is based on the lamp type and using the UV lamp 24 hours a day, seven days a week. Once this time limit has been reached, the lamp will still glow or light up. It still needs to be replaced because it is too weak to perform at optimum levels. It is usually considered 60% efficient when it is time to replace it. We offer great deals of replacement lamps here at KoiPondUV - Click for Emperor Aquatic lamps - Click for AQUA lamps - Click for W Lim lamps


Low Pressure UV Lamps VS Medium Pressure Lamps

This can be confusing depending on what you read. Low pressure puts out a very narrow area, yet a high level of UV right at 254 nanometers. The medium pressure lamps don't put out a very high level of UV, yet they do produce a very broad range of UV over the entire spectrum that enables it to potentially kill of more types of Microorganisms. (Make you wonder why we don't consider having one of each?)

What is the difference between low pressure UV lamps and medium pressure UV lamps?

Low pressure; UVS are most suitable for aquatic applications because most of their UV output is in the range of 254 nanometers, closest to what ponds need to kill Algae. They also have a longer life use than medium or high pressure lamps.

Medium pressure; lamps are commonly used in municipal and industrial plants, wastewater disinfections, compact drinking water treatment plants, photochemistry and activated wet oxidation. They're most suitable for the larger industries because their spectral radiation has a larger range that effects a larger variety of chemicals. They're also more efficient for larger flow volumes. They will still work very well at killing Algae provided the flow rates are correct. Their UV output is in the range of 200 - 300 nanometers with less intensity than that of Low pressure lamps.

Microorganisms - Most optimum wavelengths for killing microorganisms are 200 nanometers (nm) and 265 nm.

Low Pressure

(W Lim & Emperor Aquatics use low pressure type lamps)

- UV output of 254 nm
- Ambient application temp. Max 40° C/ 104° F

Medium Pressure

(Aqua Ultraviolet UV's and W Lim's Amalgam Series use medium pressure lamps)

- UV Output of 200 - 300nm
- Surface Temp 600-900°C / 1112-1652°F (Very important to keep water moving through to aid in keeping the lamp cool when the lamp is on)

Killing Microorganisms

Killing microorganisms requires slower flow rates then it does to kill Algae. UV Lights effectively kill microorganisms from within. The DNA of the cell absorbs the light forcing molecules within the cell to fuse together. Once this has taken place the cell can no longer duplicate itself causing it to die.

Microorganisms are most effectively killed by UV Lights when they are at one of two light spectrums. Either 200 nanometers (nm) or 265 nm. When microorganisms are struck at 200 nm, the DNA absorbs the light causing a photochemical reaction in their backbone, killing the cell of the DNA. But when struck by 265nm the cell of the DNA is killed by absorbing the light within its main molecules.

Hard water vs soft water

If you live in an area with soft water, your quart sleeve is allot less likely to have problems than areas with Hard water. This is because over a long period of time, hard water can begin to build up calcium deposits on your quartz sleeve. When this happens it prevents your UV lamp from being as efficient due to the buildup blocking the light from the lamp.

If you do have hard water look for manufacturers that provide models with a built in cleaner (Wiper). For example, some models have a rod that you can pull on which is mounted to a wiping device on the inside of the quartz sleeve, surrounding the UV. The biggest advantage to this type of mechanism is that you don't have to disassemble the UV and it doesn't affect the operating of the UV. Using the wiper once a week or more is recommended if you have hard water. Caution; if the wiper is binding while attempting to pull on the wiper rod, it is recommended that the UV unit be turned off and disassembled for cleaning the quartz of heavy deposits. (Consider trying vinegar to clean the calcium from the sleeve)

Parameters influencing the effect of UV

The UV dose is a combination of both the power of the lamp and the amount of time the water is exposed to the UV light. The lamp power is measured BY the intensity of the UV (mW/cm2 ) and depends on what the initial intensity of the UV is, as well as the intensity measured at a certain distance from the UV Lamp. The further away from the lamp, the weaker or lesser is the intensity is.

The most important measurement of UV intensity though, is based on the water quality of your pond. The water quality is affected by the level of compound in your water that can absorb the UV. Determining what your exposure time should be for your pond, is dependent on how much water you have in your pond and the speed in which it passes through your UV. To calculate your UV dose take the sum of your UV intensity and multiply it by results of your exposure time. OR Review the manufactures specifications and flow rates for different models. Be sure that the total volume of your pond can pass through the UV in a 3 to 4 hour time period. (Total Pond Gallons divided by 4 = MAX flow rate through UV)

Example: 5,000 gallon pond requires 1250 gallon per hour flow rate to get all 5,000 gallons through the UV in 4 hours.

(Hot climates or shallow ponds in full sun should consider passing the total pond volume through the UV in 3 hours time. (Total Pond Gallons divided by 3 = MAX flow rate through UV)


Click image to see Emperor Aquatic UV's


Click image to see W Lim UV's


Click image to see AQUA UV's

We hope this information has helped you to learn or understand more about UV lights and will consider giving us a chance to help you more in return. We are able to meet or beat other dealer prices and are happy to help you decide which model is best for your needs.

Feel free to call us with any questions. 360 588-0140