Getting Rid of Foam in Your Koi Pond

As you know, keeping your pond water balanced, stable and clear can require quite a bit of work and pond equipment. Sometimes, when the balance of the water is thrown off unsightly foam can build up on the surface. The cause of this frothy build-up is typically due to an accumulation of organic matter from things like overdue filter maintenance, insufficient filter size, lack of aeration, and overfeeding. 

If your pond is suffering from an issue with foam here are a few explanations and solutions: 

Check your pond’s water conditions:

If there is ammonia or nitrite present in your pond water, this means that there is more waste being produced in the water can then be clarified by your filter or pond plant life. Make sure to have a water test kit ready that will detect ammonia, nitrite and nitrate levels. If your water test reveals ammonia or nitrites, your pond may be in need of more biological filtration or an additive that will bring your pond back to its balanced conditions.

You may be overstocking fish in your pond:

If you carry out water changes regularly but still have foam in your pond water, you may have too many fish in your pond. Too many koi fish will produce a lot of waste which in turn leads to a spike in nitrite levels making foam appear. This can be fixed by reducing the amount of fish living in the pond or using extra filtration. You can also try adding more live pond plants that will help to use up nitrate produced by the fish.

Your filter may be too small for your pond:

If your pond filter is not correctly sized for your pond, dissolved organic solids will build up in your water and create an unbalance that can lead to pond foam. To resolve this situation you will either need to purchase a larger filter or add another smaller filter to your existing set-up. Keep in mind that there is no such thing as over-filtering so it can be beneficial to buy a larger filter than recommended.

Over Stocked Koi Pond

If none of these conditions seem to be the problem with your water, you may also want to consider the following:

Have you recently added any medications or dechlorinators? 

Some pond dechlorinators and koi medications can be very strong and throw off the delicate water balance. Monitor your water after you have suspended the use of medications or dechlorinator and see if the issue disappears. If this is the case, foam is only a short-term problem and your pond water will clear up.

Are your fish spawning? 

If your koi fish are spawning, this can cause a temporary spell of pond foam. When koi spawn they tend to flail and thrash about the water causing excess waste from the bottom of the pond to become unsettled. This, and the spawn itself, can cause disruption to the water balance and lead to foam. Observe your koi carp and make sure to check that when spawning ceases, the foam goes away. If foam persists after, it will be due to another reason.

To put it in simple terms – pond foam occurs when there is a disturbance in the pond water balance. A resolution can be achieved by pin-pointing what factor (or factors) are causing that unbalance.

As discussed, foam in the water can be a short term issue, from spawning or treatments, or it can be a more persistent problem caused by insufficient filtration, lack of filter maintenance or even too many fish in the water. While the foam in your pond is not harmful to your fish, it is a sign of a larger problem that can lead to water conditions that are not good for your livestock to live in.