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How Often To Change Pond Water & Why (Plus 3 Changing Methods)

Lindsey Stanton Profile Picture

By Lindsey Stanton

big koi pond

Just like indoor aquariums, ponds do need to be maintained. One part of this is keeping the water clean and performing water changes.

How often to change pond water, how to keep pond water clean, and how to clear up green pond water all are things that we are going to talk about right now.

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Why Change Pond Water?

Changing your pond water is not just something you do for the sake of it. Changing the water in ponds, just like in aquariums, is essential to the health and survival of the fish and the greater ecosystem.

Simply put, substances like ammonia, nitrates, nitrites, colors, odors, and other toxins will build up in the water over time, which is also true for uneaten food, fish waste, and other organic materials. These are all things that will put the health of your fish and the whole ecosystem in jeopardy.

dog watching over pond
Image Credit: iMedkova, Shutterstock

Performing weekly water changes is a fast and easy way to remove a good chunk of these substances from the water at once. It will add some freshwater to the mix and help take some of the load off of your filtration unit too.

This is not something that you can or cannot do depending on whether you have time this week. Changing the water in your pond is essential if you want to see the inhabitants live a long, healthy, and happy life.

If you need help fixing pond leaks, then check out this article for help.

Changing Pond Water – The Amount

Now, how often you change your pond water depends on the size of the pond itself. When it comes to smaller ponds, which here are classified as being under 5,000 gallons, you will want to change the water every single week, changing roughly 15% of the water each time. Larger ponds over 5,000 gallons in size require a weekly water change of 10%.

Now, if you have a super heavy bio-load in the tank (meaning lots of fish), you definitely want to stick to these numbers. But if you have a light bio-load, for smaller ponds, a 10% weekly change should do, and for larger ponds, a 5% weekly change should be adequate. Either way, performing weekly water changes is essential.

koi fish in pond
Image Credit: Dpongvit, Shutterstock

How To Change Pond Water

There are a few different methods of changing pond water, so let’s go over each of them, as one might work better for you than another. Keep in mind that the first method mentioned here is the least recommended one, but for smaller ponds, it does work alright.

Method 1 (Recommended for Smaller Ponds)

You can use a pump or siphon to drain the desired amount of water out of the pond. You can then use a hose to refill the pond to the ideal level. What you need to keep in mind here is that public water is usually full of chlorine and chloramines, which absolutely need to be removed from the water. This means that you need to use a water conditioner and treatment options to remove the chlorine and other contaminants.

Please folks, if you choose to do it this way, the water conditioner absolutely needs to be added to the pond before you add new water, not after. If you do it this way, you also run the risk of flooding the pond if you happen to forget the hose in there for too long. This method is not recommended.

koi fishes in the pond
Image Credit: NatalieStamer, Pixabay

Method 2

One of the easiest methods to use still involves a pump or siphon, but you will be treating the new water before it enters the pond. Either way, drain the desired amount of water out of the pond with a siphon pump.

The difference between this method and the first one we went over is that here you will be preparing the water first, which in all reality is easier and safer for the fish.

Measure how much water you will need to add back into the pond and put it in some kind of pool or container, or whatever else you have that can hold the necessary amount of water. Letting it stand will help chlorine and other chemicals dissipate, plus you have a safe place to add water conditioners and treatment options.

After the water has stood for about 12 to 24 hours, you can then slowly pour it back into the pond. Remember guys, do not drain out the old water before the new water is ready to go.

pond for fish
Image credit: Unsplash

Method 3

The third method tends to be the easiest for the long term, but it does take time to set up, plus is costly too. First off, you will need an overflow drain, which is a device that allows water to escape the pond when it reaches past a certain level.

You will then need a permanent water line installed that always has new water coming into the tank. You will need some kind of drip mechanism or trickle filter to slow down the water flow.

The aim here is to change from 5 to 15% of the water per week, but you are doing so constantly, with a teeny bit of new water always coming in and a little bit always going out. As we said, this method is best for larger ponds as it will cost a good deal of money and take a lot of work to set this water-changing method up.

However, once it is set up, you will never really have to do much work again in terms of water changes.

koi fish in pond
Image Credit: Kwangmoozaa, Shutterstock

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How To Clear Up Green Pond Water

If you have green pond water, it means that you have a type of algae blooming in there, plus some other substances too. Let’s talk about how to clear up that green pond water right now.

Getting Rid of Pond Algae

Green pond water is almost always caused by a certain type of algae blooming in the water. There are various ways to help get rid of algae and cut back on that green tinge.

Increase Filtration

One of the best ways to clear up green algae pond water is by increasing filtration. First of all, you should already have a good 3 stage filter in place, one that engages in all 3 major types of filtration (mechanical, biological, and chemical filtration). Mechanical filtration removes waste that can discolor the water, plus it removes waste that breaks down and releases substances into the water.

Biological filtration clears the substances out of the water, like ammonia and nitrates, which are created when waste and organic matter break down. Chemical filtration removes other toxins, colors, and odors from the water. This is important because algae feed on things like ammonia.

Therefore, a good filtration system will help cut down on green water. If your filtration system is not powerful enough, you might need to perform an upgrade, get a new one, or just get a second one. Also, be sure to maintain your filtration system and clean it regularly.

UWIOFF 10' x 13' Pond Liner
Image Credit: UWIOFF, Amazon

Decrease Sunlight

Placing your pond in an area that is not too sunny, at least not all day long, will also help cut down on green water. Algae, just like other plants, need sunlight to perform photosynthesis. Without as much sunlight, algae will not be able to bloom and therefore your green water problem should clear up.

Algae Eaters

There are animals you can add to your pond which will eat the algae as soon as it blooms. Koi fish, goldfish, frogs, and snails will all eat algae.

koi pond
Image Credit: SandraLina, Pixabay

Dye The Water

Yes, we are talking about clearing up green pond water, but we are talking about green water caused by algae. You can in fact dye your pond green, blue, or even purple in color, at least partially (more on Pond Dyes over at this article).

This will help stop sunlight from penetrating too far into the pond, thus taking away one of the food sources which algae need to bloom.

Add More Plants

The final thing that you can do to help clear up green pond water is to add more plants to the mix. First off, submerged plants will filter out things like ammonia and nitrates out of the water, thus removing the fuel that causes green algae blooms.

Second, you can add some floating surface plants into the pond, as this will help block some sunlight from getting through to the water, thus also removing a food source from the algae.

Related: 4 Key Things To Keep Guppies In A Pond

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Conclusion

Folks, the bottom line is that changing pond water weekly is essential for the health of the community. Yes, it does take some time and effort to do each week, but it is absolutely crucial, and some methods are easier than others. If you have green pond water, follow the above tips to remove it.

RELATED READ: How To Clear Muddy Koi Pond Water: 4 Methods


Featured image: Pixabay

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