Best Koi Pond Water Test Kit: Reviews | Aquascape Addiction

Best Koi Pond Water Test Kit: Reviews

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If you are on the hunt for the best koi pond water test kits then this post will help you, we cover our top picks and some essential information on why you need to test and what to look for.

Best Koi Pond Water Test Kit: Reviews

Koi ponds are very beautiful and relaxing no doubt. However, just because you have it outside instead of indoors like an aquarium doesn’t mean that you can just leave the pond to the whims of Mother Nature.

There are certain substances and compounds present in pond water that need to be tested for, some of which should not be present at all. So, we are here to help you find the best koi pond water test kit (this is our top pick) and to talk about the various substances you need to be testing for.

API Test Kit Our Top Pick 9.5/10
API Test Strips Easy To USe 9.2/10

What We Think Is The Best Koi Pond Water Test Kit

Here we have what we think is the number one pond water testing kit. This is a big kit and it will last a long time, plus it is very accurate too, both big bonuses.


This is a big testing kit that should last you for quite a while. It comes with everything you need to test for 4 main water parameters that we have discussed below. Each set comes with enough stuff to run over 5 tests (you can check the price here).

It comes with testing solution, 4 glass vials (for each of the 4 tests), and the color charts for comparison. Unlike the below 5 in 1 test strips, testing for each parameter has to be done separately here, but it is probably a little more accurate.

This kit is a little difficult to use at first because you have to get a certain amount of pond water, add a certain amount of testing liquid, and then compare each vial to the corresponding color chart for things like ammonia, nitrite, pH, and phosphate.

On a side note, this kit does not test for water hardness, so you will have to find a way to test that separately. All of this being said, this kit is probably one of the most accurate pond water testing kits in our opinion.

Click here to check the price at Amazon

Our Top Pick For Test Strips

Here we have some really simple to use 5 in 1 pond water test strips you can look at. These things are not technologically advanced like the Master Test Kit above, but it gets the job done.


These are some very simple to use test strips (you can buy them here). All you have to do to measure water parameters is to dunk the strips into the pond and then match them up with the color chart provided on the box.

These test strips will inform you of ammonia levels, nitrite levels, pH levels, GH levels, and KH levels too. That’s pretty much everything that needs to be tested for.

These strips are fast, convenient, easy to use, and you get 25 of them in a box. In all honesty, there is really nothing else to say about these strips. Unless you are color blind and can’t use the color comparison chart, simply dip the strips, compare colors, and go from there. It really does not get any easier than that.

Click here to check the price at Amazon

When Do I Need To Test My Koi Pond Water?

You should always have a pond water testing kit on hand so you can test the water whenever you feel the need. However, there are definitely certain times when you really need to test the water for the various substances, those which we will discuss further below.

Usually, you would only test the pond water if you notice that there is something off, but it is a good idea to test about once per month either way.

1. After Fish Sickness

Perhaps the most important time to test pond water parameters is when you have had fish that have been sick or still are sick. Sick koi can become ill due to any number of reasons, especially those associated with the below substances which these kits test for.

Ammonia, nitrites, water hardness, pH levels and other things can all cause illness in fish. So, if your fish have been sick, you need to test for the underlying problem.

2. New Ponds

The biggest problem with new ponds is that they have not yet gone through their nitrogen cycle. Just like aquariums, ponds need to have lots of beneficial bacteria to break down ammonia and nitrites. These bacteria take weeks and even months to develop.

You need to make sure that the water has enough of these bacteria before you put the fish in the water. A lack of these bacteria will cause ammonia and nitrite spikes, plus it will cause the pH to plummet too. At the same time, the water you are using to fill the pond may be excessively hard or soft. These are all things that can cause problems with your fish.

3. If You Notice A Change In The Water

If you notice a change in the water, which can be in the form of color, clarity, or smell, you definitely need to test the water with some kind of pond water testing kit.

If you have clear and good smelling water one day, but have water that is cloudy, stinky, and maybe full of algae the next, you need to know what is causing the phenomenon (we have covered a detailed guide on cleaning algae here).

It could be due to ammonia, nitrites, the pH level, GH, or KH. You need to know.

4. After Treatment

Another time to test the pond water is after you have treated the water. Dechlorinators, water softeners, pH adjusters, and medicines can all cause changes in pH, GH, and KH levels, which is of course something that needs to be monitored and controlled.

Always test the water after adding any kind of substance into it. For instance pH altering chemicals when not used carefully can cause massive pH spikes and drops.

5. Regular Tests Are A Good Idea

Simply put, testing the water regularly is a good idea. Often these substances will build up slowly, so regular testing will give you a heads up before the situation becomes critical. Doing a test per month is probably not a bad idea.

Ideal Pond Water Conditions

When it comes to your koi pond, there are certain water conditions that absolutely need to be met if you want your fish to survive. There are various substances and compounds which need to be closely monitored and controlled, for the benefit of your fish and plants too. There are 5 specific substances which you really need to look out for. (we have covered our 10 favorite pond plants over at this article)

These include nitrites, ammonia, pH, GH, and KH. These are all substances which should not be in the pond, or only in extremely small amounts. Let’s take a closer look at each of these substances and what their ideal levels in your koi pond should look like.


First off, nitrites are a product of the nitrogen cycle. They are created when beneficial bacteria in the tank or pond break down ammonia (something we will talk about below). These bacteria turn ammonia into nitrites.

Nitrites are not quite as harmful to your fish and the general ecosystem as ammonia is, but none the less, even small amounts of it can end up killing your fish.

There are certain factors that can cause nitrite spikes, but unless this lasts for a prolonged period of time, it is probably nothing to worry about. On that same note, having slightly higher nitrite levels in a pond than in a fish tank should be considered normal.

If you are worried about having too much nitrite in the pond, reducing the amount of ammonia present should help, so stop overfeeding fish, don’t overstock the pond, and engage in regular cleaning and maintenance.

Using a biological filtration system will definitely help too. When it comes to nitrites in pond water, there should be no more than 0.2 mg of it per every liter of water. Anything above that level and your fish are in trouble.


Ammonia is another big problem that is present in fish tanks and ponds, but should not be at all. Ammonia will literally burn your fish, poison them, and kill pretty much everything in your pond without much notice.

Ammonia is produced by decaying plants, fish waste, and rotting food. It gets released into the water, where it wreaks havoc on fish and anything else living in the pond.

If you want to reduce ammonia levels, getting a really good biological filter, cleaning the pond, doing water changes regularly, not overstocking the pond with fish, and not overfeeding your fish are all things which will help reduce ammonia levels. Unlike nitrites, even very small amounts of ammonia in the pond for a short period of time can spell disaster.

On an interesting side note, beneficial bacteria actually break down ammonia into nitrites, and then into nitrates. You want there to be as little ammonia in the water as possible.

To be fair, there is no so called acceptable level of ammonia in a pond or fish tank. Any amount of ammonia is technically already way too much.


pH stands for “potential of hydrogen” and it is a measure of how acidic or basic the water is. This scale goes for 1 to 14, with 1 being very acidic, 7 being neutral, and 14 being extremely basic (alkaline).

One of the big problems with acidity is that there is a direct correlation between it and ammonia. More of one of these things will lead to an increase in the other.

Acidity level fluctuations are fairly common and normal, so don’t worry too much if you get a slightly high or low reading once. Unless there is a really big pH spike or the level is elevated (or too low) for several days, then you have a problem.

For one, an increase in ammonia can cause pH to drop and become very acidic, so follow the steps above when we talked about ammonia to reduce the levels of it in the water. Very acidic water is not going to be good for your koi.

On the other hand, water with a high pH level, or in other words, water that is basic, is also not good. This can also cause stress to your fish and kill them. This is often caused by cement, rocks, and wood leaching lime and other basic (alkaline) substances into the water.

For most ponds, a pH level between 6 and 8.5 is considered normal. So the water can be either a little acidic or basic. However, when it comes to koi fish, the water should be between 6.8 and 7.8, so more or less neutral in acidity.


GH stands for general hardness and it is the amount of dissolved minerals in the water, specifically magnesium and calcium. A high GH levels means that there is a lot of dissolved calcium and magnesium in the water, while a low GH level means the opposite.

Different parts of the world have different levels of water hardness, and they can fluctuate from one region to another. You may live somewhere where the water is soft, and therefore has a low GH level, or you might live somewhere with hard water, or in other words, a high GH level.

Water in a pond can get harder when it is near limestone, cement with lime, or other rocks and items that can leach calcium and magnesium into a pond. In terms of a koi pond, the ideal level of water hardness is between 100 and 150 parts per million.

You don’t it to be higher than that because it will stress your koi, but calcium is essential to the bodily functions of koi fish, so you can’t have any less either.


KH is often overlooked, but it is still important to keep in mind. KH refers to the amount of dissolved carbonate and bicarbonate in the water. These work as buffers to stop the pH level from dropping or rising drastically.

Therefore, the KH levels biggest importance is in relation to the pH level of the water. If there is little carbonate and bicarbonate in the water, it will kill off beneficial bacteria that break down ammonia.

This is turn leads to an ammonia spike, which is bad in itself, but also leads to a pH drop, thus creating 2 problems at once. The ideal KH range for a pond is between 125 and 200 parts per million.

If the value of KH is too low, you can add sodium bicarbonate into the water, and if it is too high, you can add reverse osmosis water, tap water, or distilled water into the pond.

If you need help finding the right food for your Koi's then checkout this article.


Remember folks, all of the substances we have talked about above need to be monitored and controlled in order to ensure happy and healthy koi fish in your pond. You definitely want to get yourself a good pond water testing kit so you can keep track of water parameters. If you notice that something is not right, you need to change it ASAP.