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9 Reasons Your Vallisneria Is Melting!

Although vallisneria is still a pretty niche aquarium plant compared to some of the other popular options out there, it has slowly been increasing in popularity over the last year or so.

This has resulted in a spike in the number of people reaching out with questions about their vallisneria melting recently.

Although vallisneria is usually easy to care for, there are a number of common mistakes that we see people making time and time again with their vallisneria that can cause it to melt.

This is why we have decided to publish this article going over the most common causes of a melting vallisneria plant.

Our hope is that we will be able to help as many of our readers as possible get a better idea of what the problem in their tank may be as well as what they should be trying to do to actually fix the issue in their tank with their vallisneria.

Why Your Vallisneria Is Melting!

Here is our list of the most common causes of your vallisneria plant melting in your aquarium but we will cover each point in more detail below:-

  • Water Flow Problems!
  • Bad Water Quality!
  • The Tank Placement Is Wrong!
  • Problems With pH Level!
  • Water Parameters Changing Quickly!
  • Issues With Light Intensity!
  • CO2 Levels!
  • The Ammonia Cycle!
  • Algae Levels Are Too High!

If you are new to keeping a planted tank then some of these are very common mistakes for beginners to make.

This means that your tank may actually have more than one problem with it causing your vallisneria to be melting.

“Betta in Vallisneria” by Saverio Savio is licensed under CC BY-NC-ND 2.0. To view a copy of this license, visit

Water Flow Problems!

One of the most important things for a healthy planted tank is having the correct water flow.

If your water flow is too high then this can cause a number of problems for your plants including causing them to melt.

The issue is, vallisneria is that there are actually a number of slightly different types of vallisneria that are commonly miss sold as different types of vallisneria.

The natural habitat for vallisneria can range from no water flow ponds and pools to high water flow rivers.

This wide range of required water flows as well as how problematic it can be to correctly identify your type of vallisneria can be a real issue.

Thankfully though, most types of vallisneria can work well in a low water flow tank even if it would naturally be found in a high water flow area in the wild.

Problems With pH Level!

One of the most important things for a healthy planted tank is having the correct pH level.

Your vallisneria will usually need a pH level of 6.5-8.5 but in some situations, this can be tweaked slightly with minimal issues.

Unfortunately though, in other situations, even the slightest change to the pH level of your tank can cause problems with your vallisneria with the plant melting being one of the more common symptoms of issues with pH.

Thankfully, problems with pH level in your planted tank are usually very easy to detect and correct so this shouldn’t be too difficult for most people to fix.

Water Parameters Changing Quickly!

So many beginners do a full or large water change in their tanks causing a rapid change in water parameters when in most cases, this is not needed.

The majority of people will usually just need a 15%-20% partial water change per week to maintain a healthy tank.

Anything over a 50% water change will usually change too much of the tanks internal ecosystem at once and cause problems.

Although rare, in some cases this may result in your vallisneria melting, especially if you are doing a full or large water change once per week over an extended time period.

Thankfully, in most cases, you can just adjust the volume of water you change and your vallisneria will recover.

CO2 Levels!

CO2 levels in your tank not only need to be consistent but they may need to be higher than usual for your vallisneria to thrive.

The issue is that many people try to use a synthetic CO2 product rather than actual CO2.

Although these synthetic products can work well for some plants, the can cause your vallisneria to melt.

This means that you usually have to be careful or use alternative methods to provide the tank with more CO2 to prevent the plant from melting.

We have seen a number of people notice that their vallisneria is weak and losing color due to issues with CO2 levels then try to correct the issue with a synthetic CO2 product only to make the situation worse!

Issues With Light Intensity!

Some types of vallisneria need high lighting intensity but this is rare, especially when kept in an aquarium but most types of vallisneria need low to moderate lighting intensity.

In most setups, anything over 150PAR will be too much for your vallisneria but we have seen some tank setups running 250PAR lighting causing the vallisneria to eventually melt.

Thankfully, vallisneria is a hardy plant when it comes to its light exposure so it will usually take a while for issues with lighting intensity to cause the plant to melt.

In most cases, you will usually find that you will see the edges of the leaves starting to burn and turn red or brown while yellow patches form in the center of the leaves of your vallisneria.

If you notice this on your vallisneria then it is a good indication that you are having problems with light intensity and it’s far too high for what your vallisneria needs but turning your light intensity down should be able to fix the issue.

The Ammonia Cycle!

So many beginners make mistakes with the ammonia cycle of their tank when they first start keeping fish or keeping planted tanks.

A planted tank will need some ammonia and a decent amount of nitrates in it for your plants to live.

Although vallisneria can live in a tank with lower levels of nitrates than some other popular aquatic plants, it does still need some nitrates in the water.

This is partly one of the issues we mentioned with a full or large water change in your tank earlier in the article but there other things that can cause problems with the ammonia cycle in your tank too.

A lack of nitrates will usually cause problems with your vallisneria and in some cases, it can cause the plant to melt so always monitor your levels with an aquarium water test kit.

Algae Levels Are Too High!

Algae can cause a number of issues in an aquarium due to taking up so much light and nutrients from the water.

Too much algae in your tank can end up causing some serious issues with your vallisneria plant but thankfully, this is an easy issue to monitor.

The majority of tanks will make it easy to just see the algae growing and then you can physically remove the algae or add an algae eater to the tank to deal with the issue.

Bad Water Quality!

One of the most common problems we see with people’s tanks is bad water quality.

This can be for a number of reasons but is generally caused by a lack of filtration or not doing regular water changes.

If your tank is not properly filtered then this means that there will be a build-up of toxins in your water over time which can lead to a number of problems for your plants including causing them to melt.

We would recommend that you check your filter media to make sure that it is not overdue for a replacement and that you are doing regular water changes of at least 10% once a week.

The Tank Placement Is Wrong!

Another common mistake we see people making is placing their tank in the wrong spot.

This is generally an issue for people who have tanks that are placed near windows or in direct sunlight.

If your tank is in direct sunlight then this can cause a number of problems for your plants including causing them to melt.

We would recommend that you find a spot for your tank that is out of direct sunlight to help prevent this from happening.