How to Reduce Aluminum in Your Aquarium?

Aluminum is dangerous to your aquatic environment and your fish.

If you’ve placed aluminum products in your aquarium by accident, it’s essential to clean it out. 

To know if you have a metal-buildup problem in your tank, you’ll need to know the signs of metal poisoning in fish.

If you think there’s something in your aquascape that shouldn’t be there, we can guide you through the cleaning process. 

There are a few ways to reduce aluminum in your aquarium: 

  • Change your filter
  • Use a gravel vacuum if you can see visible pieces of aluminum
  • Performing a total water change

We’ll walk you through these steps, why they work, and also how to know when your aquarium is in danger from aluminum. 

Why Is There Aluminum in Your Aquarium?

To start, let’s figure out why you may have an aluminum problem. Some people use aluminum foil as tank covers.

This is popular for pet owners that have crabs or snails that can crawl out of their tank. 

Another way aluminum can get into your aquarium is when you may have bought subpar tank decorations that contain aluminum.

While most pet store products make sure to use high-quality materials, some cheaper items cut corners in production. 

It’s also possible for aluminum to build up if you’ve been using tap water in your aquarium.

Treatment plants use aluminum sulfate and other heavy metals to treat drinking water.

But this can change depending on where you live and how much you use. It’s only toxic to your fish in high amounts. 

Effect of Auminum on Water

If you have an aluminum problem, you’ll start to notice a change in your tank’s environment.

The water will increase in acidity as the aluminum breaks down. You should conduct a pH test to confirm you have this problem.

Aluminum will break down faster in an acidic (low pH) saltwater aquarium. You’ll need to act quickly if you own saltwater fish. 

However, though you have little more time, aluminum will still cause problems in freshwater.

If you have a significant problem, you will begin to see changes in your fish.

Effect of Aluminum on Your Fish

Aluminum is a metal that oxidizes quickly. The faster it breaks down, the faster you’ll have a problem.

In small amounts, your tank can clean itself. But if there’s buildup, there will be a noticeable effect on your fish. 

Aluminum particles essentially coat the gills of fish, making it difficult for them to breathe. If the levels get high enough, they’ll eventually choke to death.

In addition to oxygen deficiency, fish may also have increased carbon dioxide in their blood. They can also experience acidosis (acidic blood).

These effects are a much bigger threat in an aquarium than in the wild since the amount of aluminum relative to water will get much higher in your contained tank.

So even if you see information that aluminum is ok in natural water, it can be fatal to the fish in your home aquarium. 

How to Reduce Aluminum in Your Aquarium

Now let’s have a look at some methods that will allow you to reduce the aluminum levels in your fish tank

Changing Your Filter

To prevent fatalities, one of the first things you’ll want to do is change your filter.

A clean filter in good working order will go a long way to removing harmful metals. 

If you don’t think you have a considerable aluminum buildup, meaning you see no changes in your wildlife, a filter change may be all you need. 

If you are a new tank owner, remember to use some old tank water when cleaning your filter.

The tank builds up natural good bacteria. These help remove ammonia caused by fish waste in the water. 

You can siphon some tank water with a gravel vacuum and use that to clean off the filter sponge.

Old debris and blockage will be removed, but it still has the good bacteria from the old tank water. 

In addition to preserving bacteria, you should use tank water instead of tap water because of the tap’s heavy metal content we mentioned before. 

Tap water also will usually contain chlorine, which kills bacteria. We want to maintain our tank’s integrity and keep the good bacteria alive. 

Once your filter is clean, you should notice some improvement. If it is serious, you may need to change the water. 

Using a Gravel Vacuum 

If you’ve dropped some aluminum in your tank, perhaps a foil covering, you can get away with using just your gravel vacuum

hygger Aquarium Gravel Cleaner, New Quick Water Changer with Air-Pressing Button Fish Tank Sand Cleaner Kit Aquarium Siphon Vacuum Cleaner with Water Hose Controller Clamp

If you can see the pieces of aluminum floating around your tank, take your vacuum, and suck them up.

You should be able to remove enough of it that it won’t pose a threat to your plants or pets. 

If it’s substantial, visible pieces, you can even use your fishnet. Scoop any metal you see.

If it wasn’t much or in the tank for very long, you shouldn’t have a problem.

Water Change and Cleaning

If you suspect something seriously wrong in your tank, you should immediately do a total change. 

If you notice you’re having difficulty keeping the pH levels optimal or that your fish appear sick, you probably have something (even if it isn’t aluminum) infecting your water.

This means your regular 20% partial water change won’t cut it.

Perform a 50% Water Change

A 50% water change isn’t always ideal since it sets your aquarium back to new.

You’ll lose some good bacteria built up from maintaining your environment. However, if you think metal has poisoned the water, it’s necessary. 

Siphon out the water from your tank. You’re going to remove about half into a bucket.

Once that’s done, you can use algae pads to clear the tank walls of growth.

You may want to have a razor blade on hand to scrape the side of the glass if there are difficult spots. 

Clean the Gravel

Next, use your gravel vacuum to clean the gravel, if you have any.

If you have tiny fish that can get sucked in, place mesh (non-chemically treated) over the siphon end. 

You want it to be small enough to protect the fish but big enough to let dirt through. Some people improvise and use a (clean) sock.

Scrub Decorations

Clean any decorations (that you’re sure are not the cause of the aluminum) with algae pads.

Clean them in the tank water you siphoned out. Do not use soap or anything chemical-based.

Once the decorations are back and you’ve done the other steps, you can refill your tank.

Using new water, replace the 50% you siphoned out. Make sure it doesn’t go to the very top of the tank.

There should be some airspace between the surface and the top of your tank. 


Watch the pH levels, and make sure any cloudiness disappears. If this is a saltwater tank, make sure your water has reached the correct salinity. 

Finally, you can clean the exterior of your tank and change the filter to be safe.

You should have cleared the environment enough so that there are no dangerous levels of aluminum build-up.

Other Materials to Filter Aluminum

To make sure your water remains healthy for your fish and to avoid frequent tank cleanings, there are other items you may want to consider using. 

Depending on your tank’s size, you can create an aquascape that helps clean your environment.

Enough plants can remove all sorts of unwanted debris, provide oxygen, and encourage good bacteria growth. 

Some plants can even help clear heavy metals. Peat moss can absorb some aluminum, so you may want to use it to keep levels down.

Note that peat moss can only survive in a freshwater system. 

For saltwater, Caulerpa has a similar effect. You could also purchase a protein skimmer if you have a large saltwater tank.

Marine Color Sunsun Aquarium Surface Protein Skimmer 5W JY03 Aquarium Oil Film Processor JY-03 Oil Removal Filter Fish Tank Filter

It removes mainly organic material but can help with metals too. 

A somewhat expensive option is a RODI filter. A reverse osmosis deionization system reliably removes metals and other harmful materials from water.  

AQUATICLIFE Twist-in 4-Stage Reverse Osmosis Water Filtration Deionization System, RO/DI Filter Unit 75 GPD

Safe Materials to Use in Your Aquarium

There are a lot of safe options for your aquarium if you want to avoid aluminum or other metal contamination. 

If you’re making your own decorations or hidey-hole for fish, glass, PVC, silicon, and many plastics are perfectly safe.

Ceramics, like terracotta, are fine, and natural things like wood and rock are usually a safe bet. 

If you are using natural driftwood or something you found outside, be sure to boil it before putting it in your tank.

You don’t want to introduce anything toxic or any harmful bacteria to your fish. 

Even some metals, in small quantities, can be safe. Titanium, for example, won’t break down at all (though it’s very expensive).

Make sure to do your research if you want to use something uncommon. 

Wrapping Up

Aluminum contamination can turn into a serious condition if left unchecked. Buildup can destroy your tank and kill your fish.

Observe your tank for any sign of a problem.

If you have sick fish, don’t panic. 

Thankfully, reducing aluminum and other harmful metals is easy enough. Just be vigilant and act when you notice you have a problem. 

Come back whenever you need to and check the steps we’ve laid out for you here.

Other articles you may also like: