Koi Pond Water Change

Very Essential Pond Maintenance Requirement for Your New Pond

Regardless of how experienced you are as a pond keeper, when it comes to Koi fish, you've probably heard about the idea that once a Koi pond is set up, you do not need to manage it. I thought similarly once, but since dabbling into the world of Koi ponds, I've come to realize as a pond owner, that if there is one thing any Koi pond needs, it's proper management.

A Man Cleaning a Koi Pond
Regularly Change Your Pond Water to Keep Your Fish Healthy

The benefits that your Koi pond will receive from water changes are substantial enough for you to start doing them regularly if you are not doing them already. Having dirty old cloudy water is the last thing your Koi fish need in their lives, as it will only bring them nasty things that will harm them in the short and long term.

In this guide, I'll cover all the following in detail:

  • What a Koi pond water change is.
  • Why Koi pond water changes matter.
  • How often Koi pond's water needs to be changed.
  • How to do a Koi pond water change yourself.

After reading through these four main points, you'll be more than ready to start doing water changes on your own Koi pond! Not only will you feel great once you have done a regular water change yourself, but your Koi fish will feel great, and they will thank you for the new water!

What Is a Koi Pond Water Change?

A Koi pond water change is when you change the water in your Koi pond, and this is generally done in a variety of ways that all work well in their own right.

This process involves removing the old water from your Koi pond and replacing it with fresh water entirely, and if done right, your Koi pond will possess little to no traces of the dated water afterward.

Cleaning a Koi Pond with a High Pressure Cleaner
Bad Water Quality Can Lead to Koi Diseases

Why Do Koi Pond Water Changes Matter?

So, now that you know what a Koi pond water change is, you probably want to know why it matters and why you should bother with it in the first place.

Well, for starters, if you were a pond fish living in water, wouldn't you like that water to be fresh instead of old and musty? Water changes have all kinds of health benefits for your Koi.

Like any other body of water, a Koi pond can get polluted over time, and the longer a pond's water goes without being changed, the more toxic chemicals it will have.

This is not good for your Koi, as bad water quality has a high chance of leading to disease in Koi and possibly even death. It is important to note here that not all bacteria is harmful. There is also beneficial bacteria which helps maintain the overall health of your fish in your garden pond.

Two Men Cleaning and Changing the Pond Water
Water Changes Affect the Health of Your Koi

There are more nitty-gritty details that I could go into if you wanted to get the full scoop on all the ways bad water quality can affect Koi fish. However, you do not need to know those super-specific details to get the overall gist here. However, do pay close attention to preserving the proper water temperature and oxygen levels as part of your regular koi pond maintenance.

Generally speaking, polluted Koi pond water has many significant downsides without any upsides, whereas clean Koi pond water is the exact opposite. Having clean Koi pond water will improve the health of your fish in several areas, with one major one being higher reproduction rates.

Because of this, if you did not have any reason to do water changes before, then you do now. Ultimately your fish will be far happier with clean and fresh water, and that alone should be enough motivation for any good Koi fish owner to start conducting regular water changes.

How Often Should a Koi Pond's Water Be Changed?

While I was researching Koi pond water changes, the question of how frequently water changes should get done is one that I never found a definitive answer to.

This might surprise you a bit, as I was also surprised at the time. However, the big issue with providing a precise answer to the question lies in the subjective nature of Koi ponds. Every Koi pond is different, whether that difference is large or small, making it impossible to give a standard timeline for a water change.

So, rather than looking online for the answer, you'll have to figure it out for yourself once you start doing water changes. Though don't worry because determining how often you should change your Koi pond's water is not as difficult as it might initially sound.

A Photo of a Testing Kit to measure Nitrite Levels
A Sample of a Testing Kit

Start by getting yourself a water quality testing kit to see how your Koi pond water is doing, as simply eyeballing it won't work.

Next, pick a starting schedule to follow for your water changes. You'll want to do this because it is good to be consistent in implementing water changes from the get-go, rather than having a random process.

Personally, I would recommend either doing small daily water changes or large weekly ones, and the one you decide to choose will mainly depend on your personal preference. For example, if you have a solid block of time each day of the week in the afternoon to do a water change, then go with the daily schedule. Conversely, if you are busy on most weekdays, simply do a weekly water change on the weekend.

At the end of the day, whatever method allows you to best manage your Koi pond's health is the one you should opt for, so don't overthink it.

How To Do a Koi Pond Water Change Yourself

Now let's go over how to do this water change that we talked about so much.

The process is relatively simple, though there are two main things that you'll need to have on hand to successfully change your Koi pond's water. These two things are a water pump or pond vacuum for extracting water from your pond and a way to add dechlorinated water back to your pond.

While I will say that a water pump is arguably the best when it comes to removing water, the pond vacuum is no slouch in that department, and it will also clean any debris and harmful growths in your pond, which is something that a water pump cannot do.

Again, what you choose here is primarily a matter of personal preference. Still, I recommend investing in a pond vacuum for the added cleaning aspect, regardless of whether you're doing daily or weekly water changes.

A photo of a Woman Cleaning a Koi Pond
Try to Clean and Replace Your Water Yourself

As for adding dechlorinated water back to your pond, it is more a recommendation than a requirement. However, it is worth taking the extra step of dechlorinating water because it is better for your Koi Fish's health.

There are numerous ways to dechlorinate water, and you can read up on them if you desire, but I suggest getting a water filter that can remove chlorine from your water as it passes directly through a hose.

This is the easiest way that I have found, and it is highly efficient, so you won't have to worry about such a simple method not getting the job done.

When you refill your backyard pond with water, pay close attention during the process, so you don't accidentally overfill your pond. There are devices like float valves that can help automate this process, but they are not required. Just keep an eye on your water as it is flowing back into the pond, and you won't have to worry about any overflows happening.

A man using a net to clean the pond
Don't forget to Keep an Eye on the Flowing Water

Finally, once you add water back to the fish pond, you can use the water quality testing kit I mentioned earlier and check the water quality.


Whether you are making smaller water changes or a partial water change to your Koi pond, it is a necessary and life saving part of your pond maintenance. Koi fish, and fish in general, depend on new water that is free of harmful toxicity for their overall health and well being.

Changing out your water takes a long time and comes with some risk for your koi. If you don't want to deal with the headache of changing the water - or if you're rightfully nervous about the process, you can bring in an outside expert. You can find a company near you in our local koi pond service providers directory.

Frank Salvatore

In 2015 our family moved into a house south of Denver, Colorado with a  koi pond.  Since that time I've learned to really enjoy the koi fish and the pond. This blog is dedicated to providing helpful hints and information for koi pond hobbyists - as well as those of you who just inherited a koi pond and are thinking NOW WHAT?

About Me

Hey there - I'm Frank Salvatore. In 2015 our family moved into a house south of Denver, Colorado that had a Koi pond. The problem was I knew absolutely NOTHING about koi ponds.

This blog is dedicated to providing helpful hints and information for koi pond hobbyists - as well as those of you who just inherited a koi pond and are thinking NOW WHAT?
Learn More About Me

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