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How to Keep Your Fish Tank Clean Without Changing the Water?

I know from personal experience that cleaning a fish tank week after week, year after year can be tiring some days. Even when you really enjoy the fish-keeping hobby sometimes it would be nice to just skip this task altogether. Luckily, there are things you can do with your fish tank set-up to help keep the tank clean without changing the water.

You can keep a fish tank clean without changing the water by feeding fish every other day, having fish that help keep the tank clean, using water conditioners, installing a UV filter, having a lot of plants in the (freshwater) tank, having an oversized filtration system, and adding powerheads to help push tank debris towards the filter intake.

Of course, there are other ways besides what I have mentioned above to help keep your tank clean and we will touch on them later in this article. But first, let’s begin by talking about what happens if you don’t perform regular water changes and how this affects the tank…

What are the Effects of Not Changing the Water in an Aquarium?

High nitrate levels can be toxic. This is the first problem you must overcome if you don’t want to change the water frequently. Not doing regular water changes will allow nitrate levels in your tank to rise and if they get too high, the fish will die!

Algae can be a big problem if you never do water changes. You can have microscopic spores that float in the water causing it to change to a greenish yellow or brownish color. Over time, this will be a problem for aquatic life as the algae slowly takes over and alters the parameters.

The buildup of fish poop and decaying plant matter in the tank is another issue with not performing water changes and trying to keep your aquarium clean. This can lead to nitrate problems and must be dealt with right away, even if you don’t want to change the water and vacuum the substrate on a weekly basis.

These might not sound like the worst issues you can have in a fish tank but honestly, they are a problem. Not only will the tank look dirty (and the water possibly not as clear as you or the fish would prefer), but the nitrates can build-up causing toxicity in the water.

So, keeping in mind that we want to keep our fish tank clean without changing water (which would solve these issues immediately), we will now look at the ways to resolve these issues without the water change.

Best Ways to Keep Your Fish Tank Clean Without Changing the Water

In no particular order, here are a handful of things you can do to ensure your fish tank is clean without changing the water…

First off, let’s talk about nitrate levels and how to keep them as low as possible without changing out water. Nitrates typically rise because of decaying fecal or plant matter or when the oxygen levels aren’t where they should be. If you’re not changing water regularly, you still need to get the excess food, decaying plants and poop out of the tank.

To solve this problem, you need to feed your fish much less than you are currently doing so. Feeding less means less decaying food and poop in the fish tank. Twice a day is too much – limit feedings to once a day or every other day.

Unless your fish are baby fry, they don’t need to eat every single day and if you want to feed them everyday, they you need cut back on the amounts given. Feed them only what they can eat in a 2-minute time-period. Doing this will result in a cleaner, safer aquatic environment with lower nitrate levels and less algae formation.

Next, make sure anything in the tank that can increase nitrates is removed (via the filter) as much as possible. To do this, add powerheads to your filtration system. Powerheads are water movers and create extra flow in the tank. When positioned properly, they can help your filter pick-up floating food, poop and decaying plant matter.

When installing a powerhead, position it so it forces the flow of the water towards the intake of the filter. This will allow the filter intake to pick up much more debris in the tank. All you have to do is just rinse out the filter sponge once a week. That’s a lot easier than doing weekly water changes, for sure!

Speaking of filters, if you added a larger filter or a second filter, that would help expedite the decaying matter in the fish tank into the filter system much easier than a filter rated for the size of tank you own. If you had two filters and positioned them at either ends of the tank, you would have better flow and much more chances of picking up that excess poop or decaying plants.

Feeding less and adding more flow to the tank are a couple of the best ways I can think of to keep your fish tank clean without having to change the water. But that’s not all, I have more ideas, so keep reading…

More Ideas to Keep a Fish Tank Clean Without Changing the Water

There are many things you can do with your fish tank that will allow you to change the water less often and provide a better home for your fish. Here are some more ideas for you.

  • Having too much substrate gives decaying food, poop, and plants a great place to hide and rot. As these pieces of debris get wedged into the substrate and start to decay, the nitrate levels will start to rise.
  • Having just enough substrate to give plant roots somewhere to grow or to help hold decorations up is all you really need the gravel or sand for. If you are concerned about a place for beneficial bacteria to grow, then consider keeping your filtration as the spot for that.
Vacuuming aquarium substrate.
  • On top of having a filter sponge, add some bio-cubes or a 2nd sponge in your filter. This will give bacteria a lot of surface area to grow. This means your tank can have much less substrate.
  • Speaking of plants, did you know that live tropical plants feed on nitrate? It’s true, it’s all part of their growing process. Make sure to add as many live plants to your tank as possible. Plants like Anubias and Hornwort will help. With such a wide variety of plant shapes and sizes, you’re sure to find something suited for your tank.
  • Plants will also help keep algae levels low as the nutrients that the algae needs to grow is also what your plants will be feeding on.
  • One thing I do when I top up in my tropical freshwater tank is use reverse osmosis water instead of treated tap water. There are no minerals in the RO water which means you’re not adding something that will increase algae growth or nitrate levels.
  • Be cautious, however when using RO water in a freshwater tank. If you use too much too often, the water will become very acidic. In turn, you may have problems with plants (and maybe even fish) dying.


Even More Ideas to Keep Your Fish Tank Cleaner without Water Changes

A less-experienced aquarium owner will typically suggest filling the tank with fish that help clean. The problem is that these fish and other creatures such as snails and Plecostomus, produce waste as well so more inhabitants equal more poop!

If you want to give it a go however, you can put large snails and plecos in your tank and some fish that will pick at algae. You could also try cherry or other types of shrimp.

That said, be careful with some fish varieties as their names can be deceiving. For example, the Chinese algae eater sounds like it would do a good job of reducing algae however, from my own experience, it really doesn’t do as much you would expect.

Depending on how well-trained the staff is at your local fish store, most casual employees likely don’t know everything about cleanser fish. If your LFS is well-established, then chances are the employees are more knowledgeable and can be trusted with the information they provide you.

Lastly, I want to offer you some advice in keeping your fish tank clean without water changes by suggesting you invest in another piece of equipment.

A UV filter can keep your tanks water clean almost all on its own. It’s definitely an excellent investment in any fish tank set-up. A UV filter kills water-borne algae as they pass through the filter. It uses an ultraviolet spectrum light and blasts the water! If your water is anything but crystal-clear, one of these devices can make a huge difference.

It might even help keep those nitrate levels in check if your tank’s levels are rising because of organic compounds floating in the water. The best thing about these filters is that they aren’t really that costly and greatly improve the overall health of your tank.

Check out these UV filters on Amazon and learn more about them in my article on the topic which can be found here

Use Activated Carbon to Help Keep Your Tank Clean

Using activated carbon in your filter to help keep your tank clean is another option. It won’t clear up the algae sticking to everything, but it will help improve the water quality.

Activated carbon absorbs contaminants such as tannins, chloramine, and chlorine (you should still use a tap water treatment) in the water. By helping to remove those contaminants, your water will be healthier and cleaner-looking.

Activated carbon will also clean-up phenols in the water. Phenols are partially responsible for making your tank stinky. So, if you don’t want to smell your fish tank from 10 feet away, try using some activated carbon (charcoal).

One thing I would caution you on is if you have live plants in your freshwater tank. I wouldn’t use carbon all the time as this will inhibit the plants from growing to full maturity.

I used to use activated carbon all the time when I had a fish-only tank. When I added live plants, they would die off in 6 to 8 weeks. Live plants need an plenty of nutrients in the water, especially if you are not providing them with live plant fertilizer – which I wasn’t.

I took the carbon out of the filter and a week later purchased new plants. Those plants are still growing, thriving with health and I don’t give them any fertilizer. The little bit of decaying organic compounds in the tank is what helps feed the plants.

If your goal is not to do water changes but still keep your freshwater tank clean, then I highly recommend you put some live plants in the tank.


At the end of the day, everything we have talked about so far will help tremendously in maintain a clean aquarium in the absence of weekly water changes. The reality, however, is you will still have to do water changes, just not as often.

Some tanks such as dark water tanks can go a long time without a water change. These tanks are filled with plants and maybe some shrimp. They might have one display fish such as a betta so there isn’t a lot of decaying fish poop or rotting food affecting the water parameters.

When looking for ways to keep your tank clean without changing the water very often, use the suggestions I have provided in this article and proceed with care. You may have some tweaking to do but eventually, you’ll figure out what works best for you and your timetable.

I hope this article has been of help to you. Thanks for reading and good luck with your aquarium hobby!

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