FAQs...

Scroll down the list below until you find an answer that addresses your question. If you don’t find an answer to your question below please check the downloadable PDFs under the appropriate product either on the aquatic biosecurity or fish stress management pages.

If however you have a more detailed scientific question please contact us at enquiries@bradanbiosecurity.com with as many details as possible and we will respond to your question.

Q.	What is the difference between Virkon® Aquatic and other Virkon disinfectants?

Virkon® Aquatic is the registered trade mark for the specially adapted patented formulation of the most widely tested and approved virucidal and bactericidal disinfection in the world. All Antec/DuPont Virkons use the Haber Willstater reaction to harness the separate antiviral activities of oxyzones, fruit acid salts and potassium monopersulphonate, to regenerate activity continuously and also incorporate a high level of detergent for ensuring cleaning of muddy boots etc in the pig or poultry context.
Virkon® Aquatic has been modified so that while maintaining and indeed enhancing its virucidal activities, particularly against fish pathogens, it has reduced detergent activity, which is very toxic to aquatic animals. The fragrance, which is highly tainting for fish is also removed.The indicator dye used is also one which is not banned for food usage in certain countries.

Because of concerns about possible toxicity and tainting in use in aquatic sector, DuPont the manufacturer does not support or take any responsibility for any usage of any Virkon other than Virkon ® Aquatic in any aquatic usage context.

(NB Initially Virkon® Aquatic was originally intended for use only in fish farms and called “Virkon S for Aquaculture” again in a distinctive blue box. Once it was realized that it had much wider usages in angling, fish-keeping, recreational boating, skin-diving, indeed any water usage, it was renamed Virkon® Aquatic. Since it has a long shelf life some suppliers might still be supplying the 10kg product with the old label. Such has been the success of the Virkon® Aquatic tablets, however, that all stock has the new label Virkon® Aquatic.)

Q.	Is Virkon® Aquatic a medicine?

No! Emphatically not. It will not treat fish or shellfish, but it will disinfect hard surfaces, boots, clothing etc , provided they are clean. If used in a fine spray into the atmosphere, a technique known as “Virkon fogging” it will greatly reduce or eliminate airborne pathogens and also percolate through rafters or other areas of buildings otherwise not possible to access.

In addition, if added to the water in which fish are swimming, at high dilution (ca 2ppm), on a continuous basis, it will greatly reduce the level of bacteria, viruses and certain parasites which can survive in that water column and thus prevent or reduce levels of potential infection. But it does this by removing them from the WATER not the fish. It is not likely to have any significant direct effect, good or bad on the fish themselves, at these concentrations. Thus no medicinal claims are made by the manufacturer, DuPont or by Bradan Ltd.

Q.	Can Virkon® Aquatic if used continuously, affect my biological filter or my domestic septic tank?

Research by The Water Research Centre showed that even at full disinfectant levels, use of Virkon® Aquatic does not affect the efficiency of septic tanks,. However, where it is dripped continuously into Koi systems to maintain a standing level of 2ppm in the water column, it can affect biological water filters if there is no removal and replacement of a percentage of the water (make-up) once a week. Usually make up of 25% weekly is necessary where it is being used continuously to prevent or control presence of Koi Herpes Virus in the water column. Signs that the filter is becoming challenged include increased nitrate build up in the water and excessive foaming. A small amount of foaming is normal and necessary as the detergent present is essential to destroy the lipid envelope of koi herpes virus (KHV), infectious salmon anaemia virus (ISA) and others.

Q.	How often do I need to refill a Virkon® Aquatic footbath.

Provided the footbath retains its reddish colour it is still strongly virucidal and bactericidal. Once it becomes greyish brown then its activity is failing and it should be emptied cleaned and reloaded with fresh 1% Virkon® Aquatic. Footbath efficacy lasts longer if there is no rainfall into the bath to dilute it. Also if boots are very muddy, the mud should be washed off first. Footbaths are among the most important barriers to infection in fisheries as well as fish farms, and need to be rigorously managed.

Q.	My vet has no experience of disinfecting fishing equipment. How can I get a veterinary certificate for taking my equipment to fish in Iceland or other overseas country.

Concern for the parasite Gyrodactylus salaris, and the KHV, ISA and VHS viruses by all angling countries including UK means that much greater emphasis is placed on disinfecting tackle AND BOOTS. If your veterinary surgeon has no experience of fish he is still well versed in biosecurity for viruses. Ask him to give Bradan Ltd a call to speak to one of our Veterinary Fish Specialists and then he will be able to carry out all the disinfection steps with Virkon® Aquatic that are necessary and issue the all important veterinary certificate.

Application of Virkon® Aquatic for water treatment

Q.	What is the recommended concentration for Virkon® Aquatic in water?

A.	We recommend 2 to 4 ppm (parts per million) for continuous dosing in a flow through system, and up to 8 ppm for initial dosing of a closed Koi pond recirculation system. Do not use any Virkon formulation other than Virkon® Aquatic!!

Q.	What does ppm mean?

A.	Ppm means parts per million – 2 ppm means 2 parts of product to 1 000 000 parts water so you can see we are using very low concentrations of the sanitizing virucidal disinfectant,which are perfectly safe to aquatic species.

Q.	How else can concentration be expressed?

a) another means of expressing concentration is as a %
% actually means parts per hundred so 1% (or 1pph) = 10 000 ppm and 0.0002% = 2 ppm

SIMPLE TIP: to convert % to ppm multiply by 10 000

b) another way of expressing concentration is as a straight forward dilution rate eg 1:100 or 1:500 This means that for every 100 part of water or 500 parts of water add 1 part of product

SIMPLE TIP: to convert a dilution rate to ppm divide the dilution rate into 1 000 000 eg 1: 500 000 dilution rate = 2 ppm (1 million divided by 500 000)

c) concentration can also be expressed as grams per litre (or perhaps in imperial units such as oz per gallon).

SIMPLE TIP: 0.002 grams per litre = 2 ppm

Q.	How do I dose a fixed volume of water with Virkon Aquatic at 2ppm?

Remember that 2 ppm is 0.002 grams of product (see 3c above) so for example a 10 000 litre tank of water will require 10 000 x 0.002 g = 20 grams of product. 1,000 gallons requires approximately one 5gram tablet of Virkon Aquatic to produce 2ppm. We recommend an initial dose of 8ppm for a koi pond so this would equate to using 4 tablets, diluted and added slowly, below the filter inflow to the pond, to create 8ppm in a 1,000gallon pond. This will rapidly break down, to natural products, but while active it will strongly sanitize the microbial flora and particularly viruses.

Q.	How often do I redose a fixed volume of water such as a Koi pond?

This should not be done more frequently than once a week unless there is a known virus threat, and it is recommended that at least 5-10% of the water is changed at the same time, as although Virkon Aquatic breaks down in the filter system, there is a trace of detergent in the product which helps it deal with viruses in biofilms. Over time this detergent can build up if there is no water turnover. It can be detected if foaming is seen around the edge of the tank, though it rarely occurs in normal usage.