Koi Pond Filters And Pumps


When starting out, it can be very daunting trying to figure out which koi pond filter systems are needed for your koi pond, and what pond filters and pumps are all about. As you may know, a pond’s filter and pump system are the cornerstone of the ability of your koi to live and thrive in the pond.

There is no single best set up for ponds, as an ideal set up depends very much on the size of your pond (the volume of water), how many koi fish you will have, and the temperature ranges you live in.

Always speak to your local koi pond supplier and make conversation about the various koi ponds systems that he has set up, and the maintenace routine of his koi pond, including the various filters and pumps he has used.

The reason for this, is not to copy what he has done necessarily, but to ask him why he has chosen that filter (so you can learn about the functions of a filter – this is important), and what advantage that filter has above others (so that you know about the various types of filters available and their differences). When you have done this with a few suppliers and koi enthusiasts, you’ll quickly learn about what these pieces of equipment are about.

So here, we’re going to have a look at the basics that you’ll need to understand and make sense of koi pond filters and pumps. The marine ecosystem is a complex one, but an understanding of the basic principles, is where you need to start.

Let’s start with the filters.

Koi Pond Filters: The Flow Rate Needed

The flow rae that your koi pond filter should be capable of, is related to the volume of water in your pond. Generally your filter should be able to filter through your total pond volume every 2 hours.

The reason for an adequate flow rate is that the waste that’s produced by the koi needs to be broken down in sufficient speed by the beneficial bacteria that reside in the biomedia part of the filter. Also, the bacteria itself requires an adequate flow of waste in order to survive. It’s like a symbiotic relationship, and it requires this adequate flow of water in order to work.

In nature, there’s the luxury of rivers and streams to provide natural filtration in good balance, but in a koi pond, we’re creating a this happy relationship between the koi and the filter.

What Koi Pond Filters Actually Do: The Filtration Process

So, koi fish pond filters are needed in a garden pond to perform these important tasks:

1. Mechanical filtration

This means to filter out particulate matter. That is, the debris and dirt that accumulates in the pond water are cleaned out, to result in clear water going back to the pond. Koi survives happily in murky water, and is able to swim and negotiate the particulates. So having clear water is mainly for our benefit, so we can enjoy our koi more, by being able to see them clearly through our pond water. This helps us to monitor the health and wellbeing of our koi as well.

This mechanical filtration also allows water to be free of debris when the water is taken through the next stage of filtration, which is biological filtration…

2. Biological filtration

Biological filtration happens in the biomedia, where the friendly bacteria will reside. With biological filtration occurs, waste products of ammonia and nitrites are broken down, so that the pond water is chemically clean (free of these toxic substances) as well as free of sediment.

This step in the filtration requires a steady flow of clear water as we already talked about before when we talked about flow rate. If bits of matter get into the biomedia or the koi pond filter media, this will simply clog it up, and not allow enough surface area for the bacteria to live. Then the biological filtration process will stop working, and the pond will collect toxic ammonia. This is part of the nitrogen cycle of koi ponds.

3. Providing oxygen and aeration to the pond

The movement of water through the pump and filter provides oxygen to the pond water, increasing the concentration of dissolved oxygen, which is vital for survival and growth.

Note, that it’s in warmer weather that the demand for oxygen by koi is the highest as this is the time of year that their metabolism is most active. A pump and filter failure at this time is the most dangerous to the fish.

Koi Pond Pumps In Relation To Filters

Pumps work together with pond filters, in that the pumps supply the filter with the water flow required for their filtration process.

With above ground filters, there’s a pump that resides underwater that pumps the pond water into the filter. After filtration, the water returns either via a waterfall above water level, or via under the water.

With gravity fed filters, the filter resides underwater, and water is fed into it via gravity. After filtration, a pump returns the clean water straight back into the pond.

Air pumps

The filter and pump system as described above is the most important part of your pond to ensure survival of the carp.

But you may have also noticed air pumps being used as well.

These air pumps provide additional oxygen to the pond, but are not as crucial as the filter and pump set up.

In summer and hotter weather however, the function of these air pumps are even more important as the oxygen requirements of the pond is higher at these times.

Finally, bottom drains are also used in addition ot the above to help with the filtration process. But the filter anp pump set up is the most important.


New to koi fish keeping?

Then click here to see the koi fish guide that will have you go from beginner to pro within days.