UV-C replacement lamp 8w

For bacteria and algae, according to conventional wisdom, a UV unit should have one watt for every 75 litres of water per hour of flow in the aquarium. To kill parasites such as white spot, according to conventional wisdom, this level should be three times higher, on the order of one watt of UV for every 25 litres per hour of water flow in the aquarium.

High flow rates, low wattages and low dwell times are all very effective for aquarium UV devices because of an obscure scientific principle called the reciprocity rule in photobiology (a one-second dwell time in ten passages has the same effect as a ten-second dwell time in a single passage).
Roughly one watt of UV per 40 litres of aquarium water is enough to kill even white spot, even at high flow rates and low dwell times.

Genetic research with zebrafish

All major universities conducting genetic research with zebrafish (460 with millions of zebrafish) use high-intensity UV in their facilities, as do public aquariums. These devices use 225,000 microwatt/cm2/second as standard to achieve 99.99% sterilisation of even hard-to-kill organisms in a single pass through the UV device. This roughly equates to 135 watts of UV for a typical 378-litre aquarium setup, or 0.36 watts per litre.

But these zebrafish facilities use UV to do the following:

• First, they do genetic research, so it is vital that these devices kill all the fish eggs at once.
• Secondly, they try to prevent diseases from being passed from one aquarium to another. This also requires killing in one go.

So the 0.36 watts per litre is meant for sterilisation in one go with a very high killing rate, killing white spot disease in one go. Only 0.36/3 or 0.12 watts per litre is needed to kill most bacteria at once.
Because of the reciprocity rule in photobiology, this needs to be adapted for the home aquarium. In the home aquarium, with multiple passages per hour, the wattage required to kill should be based on the time it takes an organism to double in population.

Take a bacteria whose population doubles in two hours.
To prevent bacteria from taking over the aquarium, you would have to kill the bacteria in about an hour. In the average aquarium with 5X turnaround time, this would equate to converting the aquarium five times. So this would be 0.12 watts per litre divided by 5 which is 0.024 watts per litre of water, or roughly one watt for every 40 litres of water in the aquarium.

Advantages of UV sterilisers

Kills algae, infusoria (freshwater microorganisms) and some disease organisms such as white spot, in the water column (and only in the water column, not on surfaces in the aquarium). If the UV passes through the water more than four times an hour, bacteria will also be controlled.
The aquarium filter will then remove the dead bodies, sometimes in hours, sometimes in days.
Because some of the organisms in the water column are dead and no longer multiply, the number of some organisms in the water column decreases.
Because the immune system of the fish no longer needs to repel some organisms in the water column, the fish have more immune system resources available to repel pathogens.