"I have been involved with fish and fish breeding since I was 12 years old and have always had an interest in using technology to create a biologically self-sufficient system. Low maintenance with excellent results must be the ultimate aim. There are no short cuts if you are serious about keeping Koi. Do it right the first time and you have years of joy. A pond must be a delight and not a headache. I have learnt of a system which I use myself:

a High Pressure Biological Filtration System

 which has proven itself over the years."


Modern High Pressure Biological Systems

U.V. Filtration

A pond with clear water is an attractive feature in your garden and brings many hours of enjoyment and relaxation.

green pond is unappealing to look at and makes it difficult to determine whether your fish are diseased or if they have hurt themselves. Algae also poses a threat to your fish as it starves them of essential oxygen.

How it works

An Ultra Zap U.V Sterilizer will maintain a clear pond throughout the year without the use of chemicals.

The unit works by exposing the phototrophic micro-organisms (free floating single celled algae) to a dose of U.V. radiation. This destroys and prevents the regrowth of the phototropic micro-organisms.

Safe to use

Ultra Zap U.V. units have no side effects on the inhabitants of your pond or environment.

If algaecides are used, you run the risk of over-treatment and/or residual chemical build up in your pond. The inhabitants, fish and plants, of your pond are to some degree sensitive to algaecides. With the use of an Ultra Zap unit you stand no risk of this.     



is a term used to describe the wavelengths between the blue violet range of the visible spectrum and the shorter wavelength or X-rays.

The ultraviolet spectrum is divided into three separate bands:-

U.V.a From 100nm to 280nm

U.V.b From 280nm to 315nm

U.V.c From 315nm to 400nm

U.V.c  is often referred to as germicidal wavelength, because of its ability to destroy micro-organisms. The tubes in all of our U.V. sterilisers emit a wide range of ultraviolet with its most significant part at a wavelength of 253.7nm, which has been found to be the most efficient for germicidal action.

When water is passed through a U.V. steriliser, micro-organisms contained in the water come into contact with U.V.c radiation emitted from the germicidal lamp. The U.V.c radiation penetrates the cell membrane and thereby either destroys or debilitates the micro-organism.

Different micro-organisms vary in their susceptibility to U.V.c radiation. The most sensitive and hence, the easiest treated, are some bacteria and most phototrophic organisms such as those found in ponds and aquaria. Relatively low levels of U.V.c easily control bacteria, such as Escherichia Coli, which can contaminate drinking water supplies, and this is why the low level of 

U.V.c radiation has been employed by the drinking industry for many years.

The most resistant micro-organisms to U.V.c are protozoans, which may, when compared to simple bacteria, require several hundred times the radiation dose to destroy them. Generally, the larger the organism, the larger the U.V dose required to damage it. There are many hazardous and pathogenic aquatic organisms that can be controlled given the correct U.V.c radiation dose. Correct application will dramatically reduce the likely spread of most primary infections such as Oodinium sp. and Cryptocaryon, at the same time almost eliminating the risk of secondary bacterial infection, which is so often the real cause of fish loss. This is achieved by controlling the potential populations of heterotrophic bacteria, which are often associated with an unhealthy aquatic environment.


The Ultra Violet Tube weakens due to usage, and thus must be changed regularly. Even though it may still glow, the output of the tube cannot be determined by the naked eye. So regular replacement is the only way to ensure “peak performance”.

Thus the tube in the pond U.V. units should be replaced every 9 months.


Bio Filters – Biological

In order for your pond to maintain water of a high quality, it is essential to ensure that a biological filtration system is used.

ULTRA ZAP manufactures 4 sizes of HIGH Pressure Biological filters. 


Biological Filtration 

is one of the most essential components of an efficient re-circulating system in a Koi Pond and is necessary to remove Ammonia, Nitrite and Nitrate.

Millions of colonies of Aerobic (oxygen loving) Bacteria grow in our Bio filters and thus

it is essential that the pump providing water to the bio filter is continuously running 24 hours a day

Maximum operating pressure is one bar

Unit must be installed after mechanical filter i.e. sand filter or disc filter

Do not restrict outlet or reduce pipe diameter to smaller than 50mm

Install ball valve on inlet to control flow rate and water pressure not on outlet

Use media with low resistance on water flow

T-off after mechanical filter and

only pump a portion of water through unit, depending on the flow rate of pump




Maximum Flow
per minute

5 Litre

2500 Ltr

Ultra Zap Bio Balls

20 - 60 Ltr

10 Litre

5000 Ltr

Ultra Zap Bio Balls

40 - 80 Ltr

15 Litre

7000 Ltr

Ultra Zap Bio Balls

60 - 100 Ltr

25 Litre

12 000 Ltr

Ultra Zap Bio Balls

100 - 150 Ltr









Bio Balls provide an excellent surface area for bacteria colonies to grow on. Millions of naturally occurring bacteria, which live on the surface, break down the toxic waste produced by fish and uneaten food.

It is important to provide adequate mechanical filtration before your biological filters and to clean the mechanical filter regularly.

Bio Balls can be used as an excellent biological filter for marine and freshwater aquariums as well as other outdoor ponds and breeding farms.




There is an average of 13,400 Bio Balls per cubic metre

Surface area is approximately 340m² /m³

You will need approx 2 litres of Bio Balls per 1kg of fish

A 30 cm fish weighs ± 500 grams

Stock approx. 4 x 30cm fish per 1000 litre

These are approximate figures and all other parameters should be taken into consideration

It is important to remember that

biological filters can take 6 to 8 weeks to establish

 and that they need a continuous supply of oxygen-rich water and so

must operate 24 hours per day

It is also important to monitor ammonia and nitrite levels at regular intervals to make sure the biological filters are adequate

Bottom Drains are considered an essential in Koi keeping these days.

Ultra Zap carries an extensive range of bottom drains for all applications


A slightly concaved profile in your pond when fitting a bottom drain, will help the debris to pass straight through into the bottom drain, and save you a substantial amount of time, which can instead be spent enjoying your Koi.

A bottom drain is there to remove everyday waste that settles at the bottom of the pond, such as faeces, excess koi pellets and any dirt that has blown into the pond and sunk to the bottom.

The bottom drain is linked to your filter/discharge chamber and from there pumped to waste

(... easy to clean)


Planning for your Bottom Drain should be done, as it is essential that the position of the drain is correct, in order to ensure that it operates efficiently. Preferably a central position would be best with the surrounding bottom sloping down toward the drain itself, thus allowing the debris to be drawn into it.

Pipe work is important to allow free movement of the debris within the pipes. You do not want to create sharp bends, 90º corners, as these could block up and reduce flow, 45º bends are much preferred.

The pipe and drain should be concreted in and the concrete should form a saucer around the drain. Ensure the concrete goes up to and under the lip of the drain, to prevent a gap that will trap debris and put great stress on the bottom drain.