Why Are Aquarium Plants Melting?

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If you’re new to the aquarium business, the notion of tank plants melting may sound bizarre. In reality, it is but a convoluted term describing the plant simply dying off.

The causes are multiple, as we will soon see, but the underlying issue is the aquarist’s ignorance.

You shouldn’t take the term as a pejorative but rather as describing a fact. Many novice aquarists tend to regard aquatic plants as decorative elements, second-class aquatic additions.

So, they provide the fish with all the care and forget to do the same with the plants. Which, as you will soon see, can have some dire consequences for both the plants and the fish.

What Causes Aquarium Plants to Melt?

If you notice that your aquarium plants have started dying, you should immediately look for a cause.

Dying plants will not only affect the tank’s aesthetics and ruin your plant investment, but will affect the water’s chemistry directly as well.

Plants make for organic matter, and then decaying in the water will create the perfect opportunity for ammonia buildup.

Aquarium plants will generally start dying for several reasons, such as:

Nutrient Deficiency

This is a common problem in overstocked aquariums. Usually, any aquatic environment will contain a variety of nutrients, vitamins, and minerals, that will nourish plants and fish alike.

However, imbalances will occur at times, and one major cause is overstocking. Having too many fish and plants in the same environment will deplete the water nutrients faster, causing plants to starve.

Nutrient deficiencies are ultimately deadly if not addressed properly and in time. To do that, you must first identify them properly.

Here are a few markers to consider:

  • Iron deficiency – The plant’s leaves will appear discolored, either light green, light yellow, or even completely white. That’s because iron is a main component in the production of chlorophyll, aside from also being synthesized for various enzymes. Fortunately, the plant will exhibit gradual color changes, giving you time to act and fix the problem. Using a tank iron supplement designed for plants will revert the issue fast.
  • Calcium deficiency – Calcium deficiencies usually occur when using soft water during water changes. RO water is a clear culprit here since the water is very low in minerals and other nutrients. So, supplementation is necessary before performing the water change. The main signs of calcium deficiency include withering and contorted leaves and brittle plants. That’s because calcium impacts the plant’s cell stability and hardness. The solution is either a calcium supplement or simply using crushed coral to decorate the tank. The calcium will dissolve gradually into the water, keeping the plants healthy and longer living.
  • Potassium – Potassium is an especially important nutrient since it functions as a vehicle for other nutrients moving through the plant’s system. The affected plant will exhibit leaves with tiny holes and curved edges. They may also appear paler compared to their natural, healthy color. A potassium supplement is necessary to restore the nutrient levels within the normal parameters.
  • Manganese – This mineral is a key component in the photosynthesis process, without which the plant can no longer function normally. The affected plant(s) will exhibit light yellow or white patches around the edges of the leaves. If untreated, manganese deficiency will be fatal. Consider using a supplement to fix the problem.

There are other nutrient deficiencies that will affect the plants’ physiology, including magnesium, phosphorus, nitrogen, etc.

The important aspect here is learning how to identify the different nutrient deficiencies and use the right approach to fix the problem.

Lack of Light

Plants use photosynthesis to, basically, survive. The process is simple but tricky to explain.

In laymen’s terms, the plant will convert the sunlight into chemical energy, part of which will get deposited as sugars and starches, and the other part being converted into oxygen.

The oxygen is pretty much a byproduct that the plant will eliminate into the environment.

That’s what makes plants important since they oxygenate the environment, whether aquatic or atmospheric.

The problem is that plants consume oxygen to survive when there is no sunlight and produce CO2 instead.

If the lights turn off for long enough, the plant will basically starve since photosynthesis will no longer be possible.

I recommend using LED lights for around 8-10 hours per day to provide plants with the ideal environment to thrive.

This is the perfect time to mention the dangers of improper light balancing. Too little light will affect the plant, but too much of it will promote algae overgrowth.

The idea is to figure out the sweet spot, which typically rests at 1 watt per gallon.

Feel free to experiment with the wattage, though, since not all tank plants require the same lighting intensity.

Environmental Change

This problem typically occurs with new plants being brought into the environment. The real issue here is the plant lacks the necessary time to adjust to its new habitat.

This will lead to a variety of issues, most of which are related to nutrient intake.

The plant’s roots must first accommodate to being submerged since they haven’t grown in a fully submerged environment.

So, the roots are not accustomed to so much humidity, which can impact the plant’s ability to absorb nutrients from its environment. The good news is that the tank plant will adapt; it just needs some time.

So, you should only submerge the plant’s roots but keep the leaves out of the water for a few days. In most cases, the plant will lose some leaves and show some signs of discomfort, but it will eventually recover.

If the plant was already fully submerged when you bought it, this accommodation process might not be necessary.

Also, check water salinity and hardness to make sure they fit the plant’s requirements.

Ammonia Burn

Ammonia burn is a common problem in dirty tanks with foul water and little-to-no maintenance.

Because ammonia is a dangerous chemical that will affect all aquatic life, both animals and plants. This chemical is the result of dead matter decaying in the tank and being consumed by bacteria that release ammonia and nitrites.

These chemicals are usually kept in check by nitrifying bacteria that turn them into nitrates, which are far less deadly.

The problem is when the tank hasn’t been cycled (doesn’t have nitrifying bacteria), which will cause ammonia levels to spike fast.

A similar outcome is to be expected when the waste outweighs the biofilm’s capability to remove it.

This happens in overstocked tanks lacking maintenance and regular water changes.

Ammonia burns typically appear the same for fish and plants. In plants, the leaves will wither and die, displaying rusty colors and becoming paler with time.

How fast these problems will progress depends on how severe the ammonia buildup is.

To mitigate or, better yet, prevent ammonia buildup, consider the following:

  • Make sure that the aquarium is properly cycled and the biofilm is thriving
  • Remove fish waste and food residues to minimize the load that the biofilm will have to handle
  • Perform regular water changes, preferably weekly, to clean and reoxygenate the water
  • Prevent overstocking; the more fish in the same environment, the higher the bioload and its environmental impact
  • Don’t use chemicals to clean the filtration system or any other tank equipment; these could poison the water and destroy the biofilm
  • Prevent methane pockets that tend to develop in sandy substrates; you can do so by stirring the sand gently from time to time
  • Always monitor water parameters to detect early signs of ammonia poisoning

In short, ammonia levels always need to stick to 0. Any amount, no matter how insignificant, will have a visible impact on the environment and the surrounding aquatic life.

Plant Disease

Yes, tank plants can develop various diseases that could kill them off fast.

The good news is that all these plant diseases are the likely result of poor water conditions. Plant fungus is such a problem, manifesting itself in the form of white fuzz on the leaves.

Nutrient deficiencies could also be considered diseases due to their symptoms.

Other plant disorders are more specialized, like Anubias rot. This condition tends to affect plants whose rhizomes have been buried too deep into the substrate.

The rhizome will begin to rot as a result, potentially killing the plant if untreated. The plant will show signs of sickness via changes in coloring and withering leaves.

Always pay attention to the signs announcing the disorder since these will be gradual, albeit quite accelerated at times.

Dirty Waters

Yes, this one is as simple as it sounds. Most aquatic plants won’t do well in dirty tank waters.

The dirtier the water is, the more floating particles and debris that the plant has to deal with.

Unhygienic waters will disrupt the plant’s comfort level and cause significant stress in the long run.

If the water is filled will particles, the plant’s ability to extract nutrients will be hindered. Always keep water quality high to prevent such a scenario.

Not to mention, dirty waters will affect your fish as well.

To correct and even prevent the problem, you need to have a good filtration system, perform regular tank maintenance, and consider doing weekly water changes.

Keep in mind to only perform 10-15-20% water changes since changing more than that will disrupt the tank’s biofilm.

Algae Overgrowth

Algae overgrowth is always a problem in unclean tanks, lacking proper water conditions.

A lot of things will facilitate algae overgrowth, including poor water conditions, excess lighting, not enough CO2 in the water, etc.

Algae aren’t necessarily a direct threat, but they will affect the plant ultimately if you ignore the problem.

In most cases, the algae will grow everywhere, including the plants. The mass of developing algae will hinder the plant’s access to light, effectively starving the plant.

Nutrient competition will also cause issues since plants and algae consume pretty much the same stuff.

To prevent that, you need to keep the algae population in check.

Bring in a few algae eaters, keep the tank’s lighting moderate, and even trim the algae by hand if they grow out of control.

Maintaining a robust maintenance routine is also key since the dirtier the water is, the faster the algae will spread and grow.

How to Prevent Aquarium Plants from Melting?

As you have seen so far, the melting problem stems from a variety of causes, not just one. It’s only natural for the solution to also come in many forms.

In short:

  • Keep the tank water clean, well-oxygenated, and free of floating particles (as much as possible)
  • Boost the level of CO2 in the tank to prevent algae growth
  • Manage the lighting better (too much will promote algae, too little is not enough for photosynthesis to occur)
  • Make sure there are enough nutrients in the water to prevent any nutrient deficiencies
  • Look for signs of plant fungus and rhizome rot
  • Prevent ammonia buildup by maintaining a healthy maintenance routine, including regular water changes

The good news is that plant melting is a gradual process that will give you enough time to react to what you’re seeing.

And you better see it since the notion of ‘melting’ pretty much describes the process of dying.

Can You Save Melting Aquarium Plants?

It depends. Sometimes you can save melting plants, other times, they are beyond saving.

It all comes down to the reason for melting and how severe the issue is. Fortunately, most aquarium plants are quite hardy and showcase an incredible capability to adapt and regenerate.

If you notice your plant is melting, assess the situation to identify the causes.

Doing so will help you understand the proper measures necessary to fix the problem.


Plants require just as much care as fish do.

More importantly, the healthier the plants, the more stable and well-oxygenated the tank water, which, in turn, helps the fish.

Plants are part of the ecosystem, and you should provide them with the care necessary to thrive.

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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