Do Live Aquarium Plants Actually Clean Water?

Live plants are stunning in your aquarium, and I absolutely love them. I have live plants in all my tanks, and although they can sometimes also be a little bit of a pain, they can also help us with the maintenance of our aquariums.

But how do live plants help? Do they clean the water? Yes! All live plants that you keep in your aquarium clean your aquarium’s water. The live plants that you keep in your aquarium actually feed on the waste of your fish. They also help in reducing algae growth.

Of course this is amazing, but there are a couple of things you do have to take into account. There is for example a scenario where live plants may even contribute to an abundance of ammonia/nitrites, which is when the plants decay.

I have organized some crucial factors in useful subheadings, and when you take these points into account you will love your live plants even more.

Do live plants consume ammonia

There are a lot of people out there that think that live plants consume justammonia. This is not the case, although I understand very well why people think this.

Instead of consuming only ammonia, the live plants consume ammonia, nitrite and nitrate, which are all the different stages of the nitrogen cycle. For all of you who are not familiar with the nitrogen cycle, here is a short recap.

ammonia -> nitrite -> nitrate

The nitrogen cycle is the process where beneficial bacteria that are housed in your biological filter media, as well as in your substrate and on the glass and ornaments, break down ammonia into nitrite and finally into nitrate. Your fish are the main sources of ammonia (as well as uneaten food and other decaying material) in your tank, and ammonia is super bad for your fish. It is already toxic and lethal in super low concentrations.

This is also the reason why we have to wait about a month before adding new fish when we set up a new tank. If we add fish too early, we have a source of ammonia (the fish) without any bacteria that can transform that ammonia to nitrite (also toxic, but less toxic) to nitrate (now we are good to go).

Can Live Plants Substitute Water Changes

Can the endless water changes go when you have enough live plants in your aquarium, as they will do the cleaning for you. It is a rather controversial topic in the hobby, because there are a lot of people who do not do their weekly or bi-weekly water changes.

Instead, they just top off their aquarium when a part of the water has evaporated and rely on their live plants to keep the water quality pristine. I do not endorse this technique, and I will explain why.

The reason why I am not a big fan of people promoting the no-water-change route is also called “old tank syndrome” by a lot of people. Old tank syndrome is common for tanks that do not get regular water changes, and basically is an accumulation of waste in your tank.

This is mostly applicable to nitrate and phosphates, which are not toxic at reasonable concentrations, but there exists a point at which your fish will suffer from their owners not wanting to do water changes.

During my research on how to explain old tank syndrome I have found an analogy used by www.thesprucepets.com for which I definitely have to give them credits. They compared a fish tank to a house, everything is pristine at the beginning, but as years pass dust and waste will accumulate under couches, cupboards and other places where you might not see them.

Your tank will look clean, but all the plant parts and other organic material has accumulated somewhere in your tank, most of the times in your filter. You can not see it there but it will decay as it has not been taken out. And of course the nitrogen cycle will break it down to nitrates, but even that is toxic at too high concentrations.

What you can consider is measuring your water parameters to see if it is necessary to do a water change, instead of doing a water change on a schedule. But this would be your choice to make. 🙂

Does adding live plants reduce algae growth

YES! Yes it does. Not directly though, here is why. They compete with the algae. Essentially algae and live plants are not much different. I know that algae are not plants nor animals nor fungi as most of the algae are single celled. But they are similar to plants because they also eat nitrate as their food.

So what usually happens when there are a lot of nutrients in the water is that you risk the possibility of suddenly seeing a lot of algae grow in your aquarium. Not ideal. First step is always doing a water change to dilute the concentration of nutrients and also removing some. But what I also recommend is the following.

If you do not have (many) live plants, it is a good idea to think about adding some fast growing live plants. This can definitely help you in keeping your algae to a minimum, as a lot of the nitrates, phosphates and

What do live plants do when your water is clean

It might happen that you have added some plants that helped you battle a spike in nutrients, and when they were doing extremely well for a couple of weeks, their growth stagnates. This can and will definitely happen if you add plants and do not add any fertilizer after that.

The nutrients levels have gone back to normal, but your plant (especially when it has been growing furiously) still needs fertilizer to accommodate its demand for food. Therefore make sure that you add enough fertilizer to your tank if you think that this will be necessary.

A good thing that live aquarium plants do when you have clean water is keep it clean! If you plants are growing well you will experience hardly any algae growth.

Are there live plants that do not clean water

The short and quick answer to this question is: no, all live plants that you add to your aquarium will help you clean your fish tank. They will also help keep your tank clean. There is a scenario however, where live plants are not beneficial for your aquarium. Where they can even pose a threat to the health of your fish.

If your aquarium plants are not doing well, for instance when you do not provide them with their needs, they will eventually start to decay. You need to stay on this, because all the plant leftovers that will flow freely throughout your aquarium will get stuck somewhere.

This can be in your filter, in the corner where you do not see them or just floating in plain sight. At first this is no problem, but when the leaves start to decay the plants that once helped you clean your tank are now a major source of ammonia and nitrites.

Related Questions

How do I know if I have an abundance of nutrients in my water? In this article we talked a lot about using plants to lower a nutrients spike, but how do we know if we even have one? To know this, you can test your water using a test kit, or you can let someone at your local fish store test your water.
Another way is recognizing a sudden increase in algae growth. If you suddenly see a lot of algae growing throughout your tank, it is a good indicator that you have a lot of nutrients in your water.

What is a good fast growing live plant to add to my tank? A plant that I have been recommending for a long time is called Elodea and is a rapid growing stem plant. It is widely available so chances are that your local fish store will have some. You can plant them in substrate or let them float in your tank. They do not require CO2.

I have live plants, but they are not doing well, what is wrong? Plants can be extremely difficult to keep sometimes. I myself have struggled with them in the past, and I have found myself asking what in the world was wrong with them. If you plants are not doing well, it means that they are missing something. Plants need light, CO2 and fertilizer.

Look up how much light your plants need, if the water parameters (pH, temp, kH) are ok and if they maybe need added CO2. Finally check your water parameters to see if there is enough fertilizer (basically food) for your plants to grow. If this is all good your plants should do well.

Bart Sprenkels

I have been keeping multiple aquariums since I was 18 years old. Just like many of you, I started with two goldfish but quickly learned they were not suitable for aquariums. Later, I switched to a tropical community tank and I also have two pet musk-turtles in a bigger aquarium. You can read more about me here.

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