Foamy pond surface. Why?

Q: I understand that good water quality is perhaps the most important way of ensuring healthy Koi, and as such, parameters like ammonia, nitrate and pH should be kept within their recommended levels. But what about other measures of water quality, such as how foamy your water is, or how cloudy it is? Obviously you can’t measure these levels in the same way, but how do you know what is an acceptable level of foam or cloudiness? Is foamy or cloudy water harmful to Koi? What causes it? And how can I prevent it? Are there any sure-fire ways of ensuring crystal-clear water?

A: Dear X

You are right to put a lot of emphasis behind the key parameters of ammonia, nitrite, pH etc as these will have the greatest influence on the health of your koi. However, I also strongly believe that there are many other factors that can also influence the health and stress-status of our koi. I feel that at times we can focus in on those few key parameters (because we can test for them quite easily) and be guilty of assuming that if they are as desired, our koi should be in tip-top health. If we had the necessary test kits we could test for some of these other factors while perhaps our attention is not drawn to other influential environmental factors as being key parameters because they cannot be identified or quantified by using a test kit (eg ‘foaminess’).

As you suggest in your letter, you are conscious that even with say ammonia and nitrite at ‘zero’, pH stable between 7.5 and 8.5 and nitrates less than 50ppm there’s still room for improvement with regards to your own water quality. You have cited cloudy/foaming water as factors that would not register on a test kit, and yet you’re still concerned about their impact on the health of your koi – (I’m also wary of the other factors that we cannot see or test for). So what about cloudy/foaming water – and its impact on koi health?

What causes cloudiness? By cloudiness, I assume you mean discolouration or tinting of your water which is till clear, but coloured. This is in contrast to a cloudiness caused by, say, suspended particles (clay, algae etc). In a mud pond, which is widely regarded as being the premier environment for koi, the water is ‘thick’ with a mix of suspended clay particles, silt and algae. These combine to produce a very stable, supportive and mineral-rich environment for koi and yet would be quite out of place in a typical koi pond. So the question as to whether cloudiness is detrimental depends on both the type of cloudiness and the context in which koi are being kept (i.e. in a mud pond or a clear and filtered pond).

Tinged water is caused by an accumulation of dissolved organic compounds that when dissolved in your pond water, absorb and reflect light, changing the appearance of your water. Sometimes in extreme cases, pond water can look like weak tea, but any accumulation, however small, will cause the white koi in your pond to change to an off-white – indicating that you should address the problem (even if your koi appear to be behaving normally).

What causes foam?

Tinged water and foam are usually experienced together as they are caused by an accumulation of the same DOC compounds. Where water is disturbed or agitated at a venturi or waterfall, then the bubbles that form, rather than bursting will remain, and drift around the pond surface for minutes until they do eventually burst.

These bubbles are formed through the stabilising properties of complex dissolved compounds. These largely organic compounds, build up in the water over time to levels which encourage stable bubbles to form.

Dissolved organic compounds build up through the metabolism of koi and other aquatic organisms, depositing the products of digestion into solution. Protein levels within the water can also increase rapidly through the inappropriate use of higher protein diets, which can leach other soluble compounds into the water, leading to the formation of a foam.

Such organic compounds are not broken down by the bacteria that process ammonia, nitrites and nitrates but by a host of heterotrophic bacteria that go to work on this diverse range of pollutants. These bacteria are oxygen consumers and are often unable to completely breakdown these organic compounds. In extreme cases, this can lead to the discolouration and foaming of pond water.

Other likely causes of foaming.

Spawning activity. From my experiences of farming koi, a foaming pond was a useful indicator that showed the koi were mid-spawn. The release of copious amounts of organic and proteinaceous matter (in the form of eggs and sperm) into the water would lead to the formation of stable bubbles – particularly around water inlets. This bubble-forming phenomenon is used to good effect in protein skimmers that can be used to remove DOC very effectively.

It is also common for water to foam as a result of excessive algae growth. Even if this is controlled by a UVc, the proliferation of single celled algae can cause water to foam through the organic compounds that are abundantly released into the water.

The use of certain medications or pond additives, particularly those containing Vitamin complexes (water conditioners) can also cause the water to foam, detracting from the spectacle of a calmed pond.

Is foaming or tinged water harmful to koi?

The reason why there are no mainstream tests available to quantify the DOC levels in a pond is because they do not pose an acute threat to our koi (unlike ammonia or nitrite). They can however present water quality issues that threaten our koi’s health over longer periods – affecting them indirectly.

How will an accumulation of DOC in your pond affect the health of your koi?

Filter performance. DOC attracts bacterial activity which in turn leads to a greater demand for oxygen from your system. This can cause the performance of ALL aerobic organisms (including your koi) to suffer. Just as an accumulation of solid organic material in a settlement chamber is undesirable, so too is an accumulation of DOC, as they will both attract bacterial activity. This means that the number of heterotrophic bacteria in the pond will increase bringing with them an increased demand for oxygen, and the potential to load the pond with toxic by-products such as ammonia.

Dissolved oxygen – a direct impact. Oxygen that is available to your pond system must first become dissolved in your pond water. There is a limit as to the quantity of solutes that can dissolve in water – so if it is already loaded with levels of DOC, it will be unable to hold as much DO as an ‘unpolluted’ pond. It is for a similar reason that we should always add additional aeration during any pond treatments.

Solving the problem.

As it is the accumulation of soluble organic compounds that assist in the formation of bubbles, regular and frequent partial water changes should prove successful. The simple act of diluting old pond water with purer, less organic-laden tapwater should reduce the formation of bubbles.

Bearing in mind that the most likely route through which organic compounds enter the water is through food, it may be prudent to try different diets to find one that will reduce the tendency for your pond to foam. Excessively high protein levels, or diets that leach significantly quicker than other diets will also lead to the annoyance of bubbles. As these can fuel the onset of algal growth, such measures will also reduce the occurrence of excessive algal growth and their secretion of proteins into the water. It is for a similar reason that I do not advocate the pre-soaking of food. It is unnecessary as an aid for your koi’s digestion, and will pre-leach the water-soluble nutrient prior to you offering the food to your koi – giving these nutrients a fast-track route into your pond water (rather than your koi’s gut).

Protein skimmers. If bubbles want to form, then why not encourage them to do so under controlled conditions in a pond protein skimmer? Borrowed from marine fishkeeping, several pond models are available, and through the vigorous aeration or water movement encourage the formation of a protein-rich foam which is collected and then removed from the pond water. This innovation for ponds is probably the most intriguing and reliable method of reliably keeping tinged water and foam to a minimum.

10 top tips for a crystal clear pond. A – For particulate matter

Dedicate as much filter area as possible to mechanical filtration

Make sure all particulate material is free to leave the pond (via bottom drain or pump)

Install a surface skimmer as this will a. provide a perfect glass-like water’s surface for viewing and b. intercept particulate matter before it can become waterlogged and sink to the pond bottom.

Ensure there is sufficient turnover to remove particulate debris – especially if a UVc is installed.

Ensure planted baskets (if you have any) are intact and not losing soil into your pond.

For foaming or colour tinged water

Carry out regular partial water changes

Install a protein skimmer to prevent accumulation of DOC, removing them as soon as they are released into your pond

Recognising that most DOC originates from food, only offer your koi a food containing the appropriate protein content required for that time of year.

Do not pre-soak food – it encourages and accelerates leaching

Over winter, do not allow leaf matter to accumulate in your pond, as these will breakdown and load your system with DOC.

Equipment for solving foaming or colour tinged water – How a protein skimmer works.

Protein skimming or foam fractionation capitalises on the dual personality of the dissolved organic molecules and involves creating a fine mass of bubbles, encouraging the DOC molecules to create a stable foam. The foam then naturally rises above the water surface, collecting in a chamber which requires either manual emptying or is fitted with a drain to waste. When a foam fractionator is first installed, phenomenal quantities of foam (and the final brown liquid) are first formed as the DOC molecules are attracted en masse to the air/water interface. Over time, as the DOC concentration drops, so does the rate at which the foam is formed and liquid ‘protein’ removed. When run continuously, once it has cleared the residual problem, it should keep on top of any subsequent DOC accumulation.

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