7 Reasons Your Aquarium Plants Turning Brown (& How To Fix It)

Last Updated on 2023-08-05

One of the first things people do after graduating from a goldfish bowl is grab an aquarium large enough so that they can keep underwater plants in with their fish.

Always a smart idea (when done correctly), the right plant life in your tank can transform the space from a water-filled glass enclosure to a mini underwater world – with a whole bunch of benefits, too. Plant life keeps tank water cleaner and healthier, and it adds a lot of life and vibrancy to your setup, too.

At the same time, adding plant life has to be done strategically. You don’t want to just dump a couple of plants in the fish tank and hope for the best. On top of that, you want to be sure you’re taking just as much care of your underwater plant life as your fish and any other aquatic creatures you’ve got in there.

Without diligent care, it’s not at all uncommon for aquarium plants to start to turn sickly shades of brown and yellow. If left ignored, those plants are going to die off and could really mess with the balance of the underwater environment you’ve been trying to craft.

 Thankfully, though, most aquarium plants are a lot heartier and more resilient than you might think.

When they start to turn different shades and colors, you should take it as a sign that they need a little intervention. Below we dig into how you can solve these problems in a hurry, but also how to get out in front of these issues so that you don’t have to worry about them happening again in the future, too.

Let’s jump right in!

Why Are My Aquarium Plants Turning Brown?

There are a couple of different reasons that your aquarium plants can begin to turn brown, but the three most common reasons are:

  • Nutrient deficiencies
  • Not enough quality light exposure and
  • Your plants (possibly) not being planted properly, to begin with

These are certainly the first things that you want to look at when diagnosing your brownish aquarium plant life. The odds are pretty good that if you get these three things adjusted, your plants will bounce back in a hurry.

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Plants are Becoming Nutrient Deficient

Plant life in your aquarium requires some key micro and macro nutrients to thrive, and those nutrients getting thrown out of whack even just a little bit can often be enough to turn your plants brown, if not kill them outright.

Most underwater plants are looking for a “diet” rich in magnesium, nitrogen, and potassium, with a little bit of phosphorus thrown into the mix as well.

Iron, manganese, and phosphates are also key pieces of the aquarium plants’ nutrient puzzle.

There are a variety of water testing kits you can buy from reputable aquarium suppliers that allow you to quickly test your aquarium water for these nutrients. Figure out what your plants are looking for specifically, test the water, and then adjust your water conditions to make sure that your plants are getting everything they need.

Not Enough Quality Light is Hitting Your Plants

Another of the most common reasons your plants begin to brown is because they aren’t getting enough light.

Figuring out exactly how much light your plants need can be a bit of a guessing game at first, especially if you have different kinds of plants underwater. Some plans are going to be a lot demanding when it comes to light, while others are going to thrive in more shaded conditions.

Striking that balance perfectly is critical, though. You don’t want to be “burning” shade-hungry plants, but you also don’t want to be “starving” plants that love a little more time under light.

A good sign that you are underlighting your plants (aside from the brownish hue they have started to take on) is a sign of brown algae on your plants.

Brown algae thrive in lower light conditions. If you’re starting to notice brown algae bubbling up all over your plants, it’s probably a good idea to leave the light on a little longer.

Plants May Not Have Been Planted Properly to Begin With

Finally, it’s critically important that your underwater plants are planted properly straight out of the gate.

Every individual aquarium plant species has its own unique planting requirements, substrates that they do really well in, and techniques for “cementing” them to your aquarium tank in a way that lets them thrive.

You need to treat the roots right, or these plans are going to brown and die faster than you would have thought possible.

Jump on YouTube, watch a couple of videos about how to properly plant the specific types of aquarium plants you’re looking to put in, and follow those video guides to the letter.

That should clear up these problems completely!

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Additional Causes for Brown Aquatic Plants

There are some other root causes that can contribute to your plant’s browning, and it’s a good idea to look for these issues if you’ve already squared away the three we highlighted above.

Poor Water Quality

Everything underwater is going to suffer if your water conditions aren’t clean and clear.

It is critically important that you have a regular maintenance schedule you stick to in order to keep your tank water as consistent, balanced, clear, and clean as humanly possible.

Dirty water leads to the browning of your underwater plants, but it’s also going to wreak havoc on your aquarium life in general.

Plants Need Some Time to Adapt

Plants might brown a little bit immediately after being submerged in their new environment just because they need time to adapt to new conditions.

It isn’t at all unusual to see some browning on underwater plants when they’ve been newly transplanted.

If you see browning on new underwater additions, give them a week or two, and then check back. You might be surprised at how quickly they bounce back after adapting to their new environment.

Carbon Levels Could Be Off

Improperly balanced carbon levels (especially when combined with lower water temperatures) can cause your plant life to be brown if not die off completely.

Aquarium heaters are almost always recommended, but you’ll also want to look for ways to increase CO2 levels in your tank regularly. Plants thrive when they have plenty of carbon in their environment – just make sure you don’t go crazy and ruin life for all the rest of your underwater pets along the way.

Substrate Might Not Be Compatible with Plant Life

The wrong substrate “holding” your plants in place may actually be contributing to their browning.

Different types of substrates are recommended for different types of underwater plants. Some substrate options are more “porous,” not holding a ton of nutrients and not restricting underwater plants and their root movement all that much.

Other substrate options are a lot more “solid”, not only holding nutrients in place so that a plant can stock up but also helping to add a little structure to the plant life at the same.

Be sure that you research the right substrate options for all the plants you’re thinking about adding to the mix.

How to Turn Brown Aquarium Plants Green Again

If you are struggling with underwater plants that are already beginning to turn brown, you’re going to want to pay close attention to the inside information highlighted below.

Consider Replanting

If the browning has become significant, and a lot of your plants are suffering from the same amount of browning, it’s probably a good idea to pull your plants and then replant them.

This is especially important if you are using different kinds of substrate. You want a substrate that is kind of loose but still dense enough to add structure to your plant root system. At the same time, you want to avoid compaction, or your plants are going to starve.

Once again, read and research how each and every one of the plants you are adding to your tank wants to be planted in an aquarium. Confirm the type of substrate that they do best with and try to group them with similar plants with similar requirements.

Replanting might be all that’s necessary to bring these plants back to life!

Bump Up (or Dim Down) Your Light Levels

Lighting levels are another big piece of the puzzle when it comes to the health and wellness of your aquarium plants.

As highlighted above, though, not all aquarium plants are looking for the same amount of time under lights.

Certain plants are going to really thrive when they get a ton of energy from light, whereas other plants are going to require a lot more time in shade or dark conditions.

No matter what, make sure that you have invested in a high-quality LED light source that you can either manually control on a specific lighting schedule or set to run automatically, dimming and brightening the lights the way you would have on your own.

The right amount of light will always kill off any brown algae that had started to choke out your plant life. That’s a surefire sign that things in your tank are getting back on track.

Be Smart with Tank Plant Fertilizers

Plant fertilizers (especially those that add a lot of extra nitrogen and a lot of extra CO2) can be a huge boost for the underwater foliage you have in your aquarium – but you need to be smart about how you add these elements to your water.

Some people get a little heavy-handed with fertilizers when they want to bring their plant life back to life. The plants inevitably respond really well (especially if they were starving for nitrogen and CO2), but you run the risk of messing up the pH and chemical balance of your water at the same time.

Your plants might be happy getting everything they need. But what about all the other underwater life you have in your aquarium?

This is why we always recommend that you have a “light touch” when adding any plant fertilizer or CO2 into the tank. The last thing you want to do is kill off your fish while trying to save your plants.

Ramp Up Your Maintenance Schedule

Every responsible aquarium owner sticks to a pretty strict tank maintenance schedule.

At the same time, it’s not uncommon for tank maintenance to take a backseat to the rest of the things we have to do in our lives – even if our underwater world suffers for it.

A day late on tank maintenance might not be the end of the world. But skip a week (or two) of regular cleanings, and you are going to have turned your aquarium life upside down.

Clean out your water. Get your filter rocking and rolling. Add the right chemicals to dial in your water conditions. Maybe even swap out your water completely for a fresh start.

Whatever it takes to get the water back to a clean and clear environment for all your aquatic life.

How to Keep Aquarium Plants from Turning Brown

An ounce of prevention is worth a pound of cure, and the strategies below are going to help you protect your plants from turning brown in the first place.

Intentionally Feed Your Plants

Intentionally feeding your plants – making sure that they get all the key micro and macro nutrients they need (magnesium, nitrogen, phosphorus, etc.) – is always a smart move.

Obviously, this has to be done in a way that balances out the rest of your water conditions, but it’s really not all that challenging. It only takes a couple of weeks until you get the hang of things completely and can do this kind of tank maintenance almost on autopilot.

Keep the Tank Nice and Clean

Regular tank maintenance really is the main thing you can do to prevent your aquatic plant life from turning tank and dying.

Regular tank maintenance (we are talking about weekly maintenance here) not only guarantees that your water is as clean and balanced as possible, but it also means that you take the time every week to carefully inspect and monitor all of your underwater life.

This’ll help you get ahead of any browning issues that might have begun to bubble up. More than that, though, it also helps you recognize what your tank needs during these maintenance sessions to build a better, healthier, stronger underwater environment for your plants and fish.


Why Are My Aquarium Plants Turning Brown and Transparent?

There are three main reasons aquarium tanks turn brown or transparent – they are nutrient deficient, they aren’t getting enough light (or are exposed to too much light), and they have been improperly planted to begin with.

Why Are My Plants Getting Brown Around the Edges?

Plants getting brown around the edges usually are a sign of those plants going through the initial adaptation phase in their new environment. Give your plants a week or two (under close monitoring, of course) to acclimate to their new conditions and see if they bounce back. If they don’t, you want to undertake other interventions.

Why Are My Plants Getting Little Yellow Pinholes in Them?

Yellow pinholes (as well as pale or yellow leaves) are usually a sign of a carbon deficiency. Thankfully, this is one of the easiest and quickest fixes when working with underwater plants life. Just be sure not to go overboard and mess with your pH balance.

Why Are My Plants Sickly Looking, Kind of Pale and Almost Milky White?

Underwater plants that are deficient in iron are going to end up looking sort of pale and milky white if the deficiency goes on long enough.

You’ll want to sprinkle a bit of iron-rich plant food into the mix to give those plants what they are looking for. Most of the time, they’ll bounce back almost right away!

Closing Thoughts

So there you have it, pretty much everything there is to know about why aquarium plants turn brown in the first place and what you can do to cure the problem – or prevent it from happening in the first place!

As long as you are pretty diligent and smart with tank maintenance, you won’t have much to worry about when it comes to keeping your plants happy and healthy underwater.

Take some time every week to inspect your plants, looking carefully for signs of browning or yellowing – as well as for signs of brown algae.

If you do notice any of these signs or symptoms, give your water conditions a quick test. That almost always points you in the right direction for how you can best remedy the issue.

More often than not, you’ll either need to sprinkle a little more plant food on your underwater vegetation, dial in the time your plants spend under the light, or you might have to tinker with the way that your plants were planted in your aquarium in the first place.

Those three issues are far and away the most common culprits behind aquarium plants’ browning.

Luckily the remedies are pretty simple and straightforward!

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