Hydrogen peroxide H2O2
Facts for use in the koi pond
Duncan Griffiths
Duncan Griffiths Copyright FEBRUARY, 2002, D, GRIFFITHS, ALL RIGHTS RESERVED

In this article we aim to bury some of the myths about the very versatile and miraculous chemical, "Hydrogen Peroxide" H2O2, and to give the prospective user enough information to make an informed decision about
it's use, plus some facts that maybe you did not know about Hydrogen Peroxide.

As with any chemical used on organic life forms there is fine balance between use and misuse, this definitely applies to hydrogen peroxide, but benefits can be gleaned from the use of H2O2 when it is applied with caution and prudence. Hydrogen peroxide is basically plain water (H2O) possessing an extra oxygen atom (H2O2) and
is an extremely powerful oxidiser as opposed to H2O plain water, which is only mildly reactive. It is very
important to know what you are dealing with and the potential reactions from the use of Hydrogen Peroxide.

A little chemistry first to help with the understanding of Hydrogen peroxide, we will get to the subject matter later
in this article. As H2O2 is just plain (H2O) water, with an additional oxygen atom, let's discuss oxygen O2 first.


The Oxygen atom has the chemical symbol "O" for obvious reasons, oxygen is extremely reactive and can be found in literally thousands of compounds and elements. Oxygen's reactivity in certain electrical atmospheric conditions is the reason for the northern lights known as the "Aurora Borealis".
Oxygen can be dissolved into many solutes, one of the best examples of which from the koi point of view is
Water. The Diatomic Oxygen molecule is the one that most people are familiar with, is designated the chemical symbol O2, meaning the oxygen molecule is made up of two oxygen atoms
Oxygen gas is tasteless, colourless, and odourless, the liquid and solid forms however, are pale blue.
Oxygen as well as being essential for combustion to take place, is essential for most forms of life. A life form
that relies on normal or high concentrations of oxygen is called "Aerobic" and life form that exist in little or no oxygen is called "Anaerobic", although, we usually refer to these two terms when we talk of bacteria, a
bacterium is either Aerobic or Anaerobic. In a general sense most good beneficial bacteria are aerobic and
most bad harmful bacteria are anaerobic. Anaerobic bacteria thrive in a very low or oxygen-depleted
environment, but this does not automatically mean that all anaerobic bacteria do not need oxygen in order to survive; it can in a few cases simply mean that anaerobic bacteria obtain oxygen from other sources.
Nitrate NO3 is a good example. If you can break the bond in this molecule you can see that there is an
abundance of oxygen tied up in nitrate to be precise *NO3* = N (one Nitrogen atom)+ O3 (three Oxygen atoms), some anaerobic bacteria can use the oxygen tied in this molecule to survive but the net result will be detrimental for the koi keeper as the residual effect would be nitrate returning to it former un-oxidised composition NO2 Nitrite, as the Nitrite compound is harmful to aquatic life. This is the principle in de-nitrification. But that's a whole different article. It just serves as a useful illustration to show how oxygen serves to influence other chemical states. Useful Oxygen terms.
Any compound ending in "ate" or "ite" contains oxygen
E.G. Sodium Sulphate, Na2SO4
E.G. Sodium Sulphite, Na2SO3
Any compound prefixed "per" contains extra oxygen
E.G. Sodium Oxide, Na2O
E.G. Sodium Peroxide, Na2O2
Any compound prefixed "thio" contains a sulphur atom in place of an oxygen atom
E.G. Sodium Sulphate, Na2SO4
E.G. Sodium Thiosulphate, Na2S2O3


Discovered in 1840 by the German Scientist Christain Schonbein, Ozone was initially used for operating theatre sanitation at this time, but is now universally used to sanitize municipal water supplies and many more kinds of sterilisation applications World Wide. With the added bonus it will strip PCB's and organophosphates out of
water supplies.

By now we are all familiar with the term the ozone layer. Ozone protects us from the suns harmful U/V radiation, UV-A, UV-B and UV-C. UV-A passes straight through the ozone layer UV-C, which is the most harmful, is totally blocked and the ozone layer absorbs 95/98% of UV-B radiation.
Ozone gas is pale blue in colour and has a very sharp acrid smell that can be smelt as low as 0.05 PPM (Parts Per Million) and condenses to a dark blue liquid at 112 deg c. Even at very low doses it is extremely toxic.
Ozone in the Atmosphere is formed by the action of the sun's ultra violet radiation on the atmosphere, causing oxygen molecules to split into separate single oxygen atoms. In this state the split oxygen atoms will bond
together in threes to form Ozone, "O3". Ozone is termed as an oxygen molecule that has three oxygen atoms, a tri-atomic form of oxygen as opposed to O2 the diatomic form that most people are familiar with.
Ozone gas is not stable and is *very* reactive. Each of the oxygen atoms in the newly formed Ozone molecule
are not comfortable in this structure, as each oxygen atom will try to break away and bond to anything organic.
If this is not accomplished, ozone will break up and revert back to O2 in an hour or so. However, if it does bond
to something organic only one atom will be used and the residue will be O2. An aquatic application if ever there was one.

The formation and destruction of Ozone is dependent on U/V light
O2 + U/V light = O + O
O + O2 = O3
O3 + U/V light = O2 + O
So it can be seen that as long as the earth's atmosphere receives U/V radiation from the sun, the ozone layer is self-perpetuating, provided we don't continually bombard it with harmful Chlorofluorocarbons, (CFC's)

Ozone is also formed in lightning storms from electrical discharge (Arc) of lightening. That is the cause of that strange smell in the atmosphere after a heavy lightning storm, like new mown hay. It can also be formed from
car exhaust gas emissions, to cut a long story short, nitrogen is formed from combustion in the IC engine and
from that NO2 nitrite is formed and is expelled in the exhaust gases into the atmosphere, this, when subject to sunny days the U/V light breaks NO2 up to form NO and O3 Ozone.
Ozone is a very powerful oxidant second only to fluorine and as already stated is not stable at all; one of the oxygen atoms will readily break away and bond onto another substance more suitable, leaving the more the
stable O2 behind.
In the atmosphere, this extra oxygen atom will readily break away from the O3 molecule and attach to rainwater to form H2O2 hydrogen peroxide. "Hydrogen peroxide falling from the sky", I hear you say?
Well yes, in essence this does happen but as hydrogen peroxide is yet another oxidiser most will be used up on the way down to earth as the hydrogen peroxide will react with air-born bacteria, virus and other impurities in the atmosphere of our heavy polluted sky's, and in reality very little will fall upon the earth. This serves as yet another purpose of the ozone layer, apart from blocking out harmful ultra violet rays from the sun, because it readily converts to form hydrogen peroxide, this serves to helps clean up pollution in the atmosphere to some extent.

Ozone is used in the koi pond to sterilise the water. More specifically it achieves this in the pond because it acts as an oxidiser on bacteria, virus and Organics, rendering the pond water more sterile and lower in D.O.C's (dissolved organic compounds). Ozone in the pond is formed with the use of an ozone generator. The generator creates an electrical arc, or corona discharge (CD) through the oxygen molecule. This electrical excitement causes the oxygen molecule to split apart to form three single atoms, when they rejoin together it will be as O3, Ozone, again the three oxygen atoms are always looking to break away. The reaction of ozone in water, works
in much the same way as it does in the atmosphere. Some of the oxygen atoms will latch onto an organic, it may be an organic compound or an organic life form, whatever organic it bonds to will be destroyed (oxidised).
What's left will be plain H2O water. Ozone gas must never be allowed to enter the main pond system where the fish live as the free radical in ozone cares little what organic it bonds too and that organic may be your prize koi. Hence we usually treat pond water with ozone as it passes through after the end of the filtration process, being fully neutralised before entering the pond by carbon filters and / or Ultra violet light, to prevent it causing damage
to the koi. But it's important to remember that, some of oxygen atoms in ozone will bond to the water molecule as it does in a rainfall, In this event the water molecule " H2O" + "O" becomes, H2O2 "hydrogen peroxide".

O Ye of little faith, I told you we would get to hydrogen peroxide eventually.

Hydrogen peroxide.
Hydrogen peroxide H2O2, looks just like plain water and is manufactured in laboratories and chemical
processing plants for commercial use for all sorts of applications. Like ozone it is formed naturally by the action
of sunlight on water and is a natural anti-pollutant in lakes, rivers and streams.
H2O2 is one of the most powerful oxidisers know, more powerful than chlorine, and potassium permanganate. Used through catalysis it can be converted to hydroxyl radicals (-OH) and as hydroxyl radials these can be made target specific in what it will oxidise.
With over 1 billion tonnes being produced every year, some of hydrogen peroxides applications are,

Paper processing
Water sanitation, (as a replacement for chlorine)
Mining and metallurgy
Chemicals and resins
Oil refining
Food production
Timber products
Textile bleaching
And many more.

As we have seen, H2O2 can and does occur naturally in nature, in more ways than you would ever imagine possible and without its * natural * occurrence, life would be impossible to maintain. Each and every one of us manufacture hydrogen peroxide in our bodies each and every second of the day, this shows that although H2O2 can have an extremely powerful sometimes negative effects, it is also a very subtle chemical essential to all life forms that possess an immune system.
As with ozone, hydrogen peroxide H2O2 will give up its extra oxygen atom readily. As the symbol in the periodic table suggests, H2O2 has extra oxygen that is ready to be put towork.
One volume of hydrogen peroxide will give up ten volumes of oxygen as it decomposes and It is this effect that
we utilize in all hydrogen peroxide applications.
With an average pH of 2.5 dependent on strength, it is extremely acidic in water. Hydrogen peroxide is
colourless and odourless but not tasteless, it boils at 152 deg c H2O2 freezes at -2 deg c. Unlike ozone, which dissipates relatively quickly, hydrogen peroxide is a little more stable and capable of storage over longer
periods if kept under ideal conditions, i.e. free of light and contamination. In these conditions it will break down
at the rate of less than 10% per year.

When used in the medical profession and in the koi hobby, its use is extremely useful, when exposed to other compounds hydrogen peroxide breaks its bonds to give up a single oxygen atom then the residue assumes the H2O the water molecule with no harmful toxins left over, however, it's the single oxygen atom that peroxide gives up that we need to help us in several koi pond applications. This single oxygen atom as with ozone is extremely reactive, sometimes called a free radical. This free radical will kill virus, bacteria and fungus and being water based makes it an extremely useful disinfectant.

We are all told that free radicals are responsible for premature ageing and all kinds of harmful ailments, yet animal, mammals and fish all use naturally produced free radicals to fend off harmful bacteria and virus. None of us could survive without the internal manufacture of free radicals in the form of hydrogen peroxide.

We all manufactor hydrogen peroxide amongst other substances. Without hydrogen peroxide we could not survive, that's a simple fact of life.
White blood cells in the blood stream are the immune system, these are responsible for the elimination of
harmful pathogens, this occurs in a process called chemo taxis performed by phagocytes within the immune.
This occurs when an antigen enters the body (an antigen is termed, any invader of the body that will raise an immune system response) After antibodies have marked the invader for destruction a phagocyte will respond
by engulfing the antigen and consuming it. It's the consuming process that releases hydrogen peroxide,
interferon, hydroxyl radicals and various other chemicals, the process by which a phagocyte engulfs and consumes a bacterium gives off a sudden burst of oxygen from the production of H2O2, called the "oxidative burst". Free radicals from the hydrogen peroxide will oxidise and consume the antigen, in fact
ironically, the reaction effect of the free radical formed from H2O2, is so powerful and violent, that the phagocyte will itself be destroyed / oxidised in the process by the same free radicals that it released to eliminate the antigen.
It hasbeen apparent for some time now that supplementary vitamin C will help keep you healthy, now it is becoming more understood why. It is believed in many scientific quarters, that a ready and abundantly available supply of vitamin C will protect the phagocyte from its own destruction as it completes its task. Hence we should all take extra vitamin C to ward off illness. This is believed to be the main function of vitamin C to help save the phagocyte. Furthermore as toxins in the body build up, this same bacterial process of the production of hydrogen peroxide will result in the oxidation of these toxins with their release via the normal route of nitrogenous waste, keeping body toxins to a minimum

Some more interesting facts about hydrogen peroxide

Scientist have found out that because H2O2 adds oxygen to any given saturation point in water, it can be used
to our advantage as it is used to our advantage in the body quite naturally.

In early submarines, the Torpedo's motor uses hydrogen peroxide as a propellant and in fact it is still used to this day in the USSR navy as a major source of propellant fuel for Russian torpedoes. With the investigation
complete into the sinking of the USSR submarine the Kursk, it was found that a torpedo leaking hydrogen peroxide onto a metal component resulted in the hydrogen peroxide breaking down at a very accelerated rate resulting in a violent explosion in the forward torpedo room igniting the rest of the arsenal of torpedoes, resulting the tragic loss of all sailed on her.
A similar incident happened to HMS Sidon as she lay in her birth at Portland during world war two, when one of her H2O2 powered torpedoes blew up and sank her at whilst moored, you can see from this H2O2 is a powerful chemical.

One of its major uses today is as a bleaching agent in the production of the billions of tonnes of paper that we currently use World Wide.

Much is made of the use of barley straw in the pond to inhibit the growth of algae (blanket weed) barley straw in
its raw state is of no use, it needs to be decomposing, during this decomposition lignin's are released from the straw into the water, oxygen in the water oxidises this into Humic compounds, the action of sunlight on humic compounds produces hydrogen peroxide. Hydrogen peroxide is known to inhibit algae growth but not kill it. So
all the while you have barley straw in the pond plus a good supply of sunlight you also have a continual hydrogen peroxide presence.

Doctors and researches alike are now beginning to use very weak doses of hydrogen peroxide to fight many diseases, many households even keep it in the medicine cabinets. Of the diseases doctors are fighting cancer figures high on the list. Cancer is considered anaerobic in nature and thrives in the absence of Oxygen. As the body is 66% water it readily accepts H2O2 and therefore induces extra oxygen to boost the saturation point of O2 in the body fluids, in theory, this should retard the anaerobic activity of cancer
and therefore the growth of the tumour. However there is no hard evidence of hydrogen peroxide therapy accomplishing any positive cures in cancer research yet, but it is being seriously considered with some merit
and in some trial cases is being applied to the task in hand.

We have an abundance of bacteria living in our digestive system (the stomach) as do fish. These friendly
bacteria along with enzymes are used to aid digestion of the food that we eat, they assimilate protein into essential amino acids so we can absorb them into the blood stream. Some of these beneficial bacteria are "Lactobacillus species" Lactobacillus bacterium have been proved scientifically to produce hydrogen peroxide and this in turn oxidises harmful bacteria and virus in the gut and urinary track, helping prevent infections in the hostile environment of our stomach and urinary tract. However, there is a bonus to this production of H2O2, the knock on effect of the bacillus producing hydrogen peroxide,again, will increase the oxygen level in this micro environment and the Lactobacillus will proliferate as a direct result of the increase in oxygen given off by the hydrogen peroxide also anaerobic bacteria numbers will decrease (remember the good aerobic bacteria and bad anaerobic bacteria?)
Furthermore hydrogen peroxide will neutralise many compounds potassium permanganate, hydrogen sulphide and arsenic to name just a few.

So what do we use hydrogen peroxide for, as applied to koi?

Let me make it quite clear, hydrogen peroxide is available to the private individual and hobbyists in many concentrations from 3% to 35% w/v and 90% for commercial applications. In the koi hobby we only use the weaker 3% or 6% hydrogen peroxide solution, no other concentration is used or
referred to in this article.

As mentioned there is extra oxygen tied into the bond of the chemical that if released can have many effects as both an oxidiser for medical use and for the increase of oxygen into an environment, We have all seen skin infections producing puss, that will weep from the infection site, this is dead phagocytes and dead cells that
have been destroyed by hydrogen peroxide produced by your immune system We are all familiar with hydrogen peroxide as used on cuts that may be infected with bacteria, when hydrogen peroxide is applied to the cut the result is the cut/wound, foams with a cleaning action. This is H2O2 releasing its extra oxygen atom as the atom bonds and oxidises the organic's in the cut, (bacteria or dead cells), The foaming is hydrogen peroxide giving
off free oxygen in the process of oxidation This release of oxygen is of further use to us as koi keepers.

In very low oxygen saturation in a koi pond we can if the situation is critical, by the introduction of hydrogen peroxide chemically raise the oxygen concentration substantially. If we further use H2O2 in controlled protocols and do not over dose its application, we can render the koi and filter bacteria unharmed. This would be considered an emergency application only and the continual use of H2O2 should be discouraged, because of
its oxidisation effects on delicate gills of koi, but it is entirely possible to raise the O2 saturation point of a given volume of water with a specific added volume of hydrogen peroxide. We may raise the oxygen content of pond water by as much as 1ppm (Part Per Million) this may seem a very small rise in Oxygen but given that a typical healthy pond oxygen value is between 6ppm and 13ppm you can see this is a significant rise in O2 for very little input in an aquatic environment.

We can also use this for cleaning up the effects of potassium permanganate, after the use of KMnO4 in the pond we are left with a thick looking brown stain to the water, which in some cases can take up to 6/7 days to clear.
The application of H2O2 at 10 ml of 3% peroxide to 150 imperial gallons of pond water will quickly act upon the KMnO4 to clear the pond in a very short space of time so it becomes gin clear again. Again this is only needed
if you really can't stand the sight of the residual brown staining of the water from the use of potassium permanganate.

If you get into a potassium permanganate overdose situation and the koi are looking really stressed the above dose will quickly neutralise the oxidising effects of potassium permanganate rendering a stressed koi, free from any adverse effects of a KMnO4 overdose treatment. Sodium Thiosulphate, common de-chlorinator will achieve the same neutralizing effect.
Be warned hydrogen peroxide even after a single dose is deployed into the pond to neutralise potassium permanganate will still be resident for some three to four days after deployment. I.E. if further potassium permanganate doses are required several days will be needed for H2O2 to decay out of the pond, or it will quickly render potassium permanganate useless.

Used to topically treat infected wounds and ulcers 1.5% to 3% hydrogen peroxide excels, especially on infected fin edges and / or mouthparts infected with columanaries (flexibacter). On real badley infected mouth ulcers it
foams away and after its cleaned away the area in many cases can look immediately much better and less
angry, the fish feel no pain from the treatment only a slight warming feeling.

Be warned ! if treating an ulcer on the body of the fish with scales around the site, special care must
be exercised not to allow H2O2 to come in contact with healthy scales as this will result in the
oxidation of that scale and the scale will eventually die and cause further infection. Also be very
careful not to allow hydrogen peroxide not to come into contact with the gill lamellae when topically treating around this area.

So there we have it, with this article more or less finished I hope it has been of some interest and use to you the reader. This article in no way endorses the use of hydrogen peroxide. However, hydrogen peroxide does have
its uses in the koi hobby, with the added benefit that as it breaks down there are no residual toxic residues left in the pond. H2O2 simply breaks down into just plain old water and oxygen but in the end it is you, the reader that
will have to choose to use it or not.