How to Size UV Light for a Pond

Written by thomas anderson
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Maintain the clean and clear appearance of your pond with the aid of a good UV light or UV clarifier. UV lights target the most unsightly enemy of a clear pond---algae---which grows rapidly on open water ponds that are warm and full of sunlight. A UV light helps break down algae's microscopic cell walls, forcing it to clump together into a larger grouping. This makes the algae easier to filter and remove from your pond surface. Getting the right-size UV light for your pond makes all the difference.

Skill level:
Moderately Easy

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Things you need

  • Typical sunlight levels
  • Inventory of fish
  • Pond capacity (gallons)

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  1. 1

    Evaluate the typical amount of sunlight on your pond. Note what percentage of the pond receives full sunlight in comparison to those sections that are partially covered by plants, overhanging trees or other shielding features.

  2. 2

    Take stock of the number and types of fish you currently have in your pond. Larger fish who have been long-standing pond residents produce more nutrients for algae by their waste. This has an effect on the size UV light you need to acquire.

  3. 3

    Look at several manufacturer's UV lights to compare prices, but more importantly flow and gallon capacity. Match the UV light capacity with the gallon capacity of your pond. You need a high enough wattage and flow capacity to cycle the whole volume of your pond, similar to the filter flush. If the size of your pond falls between the sizes of two UV light models, purchase the larger model.

  4. 4

    Choose sufficiently sized UV wattage lights to address all the factors of algae growth in your pond. More fish, more full sunlight and a large pond generates a higher weekly algae capacity. Even with small ponds that receive a lot of full sun and have a high fish content, choose a higher wattage UV light to accomplish your algae removal.

  5. 5

    Remove algae from the filter and rinse it thoroughly each week. Clinging algae formed by the UV clarifier moves in larger chunks and thus can clog and slow the filter more often unless it is regularly cleaned.

Tips and warnings

  • Make sure to have both a pond filter and UV lights to most thoroughly clean your pond.
  • Water flowing too quickly or too slowly through the UV clarifier can hinder its effective performance.

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