How to Specify an UVC (Ultra Violet Clarifier) Hot Climates.

A question from a reader will be of interest to anyone living in a warm sunny climate.

Thank you for this really informative mail. You must be a mind reader!! We are at the pond design stage for our new house in Bali and the spec of UV lights is an obvious question. Do you have a formula for this spec?

Is it based on volume of water and flow or surface area or dimensions? I am familiar with water treatment plants that contain UV lights in the final water circulation loop, but imagine that the spec here is different because of the solids content and bioload?

Also, one of the pond will be a rooftop reflection pool that I am hoping to put water lilies in. I am not planning to include fish in this one as it will be in full sun for most of the day - does the same treatment apply?

regards

Bev

My Answer

Hi, Bev

Thanks for the email.

There is no definitive formula for specifying an UV ... what you are familiar with is UV sterilisation as distinct from UV clarification. In a pond we talk of UV clarifiers.

The specification for pond is much lower than for a steriliser.

Here's are rules of thumb I would recommend for fish ponds normally stocked, allowing for normal feeding and normal growth rates in hot climates

For every 1000 litres of pond water a minimum of 5 watts

The UVC should include a quartz tube ... if it doesn't then double up the required wattage per unit volume.

Most manufacturing specs are considerably less than this.

You should

1. Replace the lamp every 8000 hours or less

2. You should check the quartz tube for film build up (organic or inorganic) occasionally.

3. Unlike sterilisation where flow rate can be critical this is not the case for a pond. Of course the UV should run full and not have a trickle of water flowing through it.

In theory no need for an UVC in a pond with no fish ... in practice you might want to add one later.

Maybe a better alternative for your second pond is to use Viresco at low rate very occasionally.