What’s Wrong With My Aquarium Plants?

Kate Barrington
by Kate Barrington
Your aquarium plants aren’t thriving. Quite the opposite. In fact, it looks like they’re about to go belly up! Here are the most common problems you’ll come across with aquarium plants.

We all like having nice plants in our aquariums. That’s a fact. It transforms a clear fish cage into a vibrant underwater environment and turns any room into a personal aquatic playground. The only trouble is that adding living plants to your aquarium isn’t exactly a “set it and forget it” proposition. Nope, these are living plants after all. They requite love and care. It’s not as if you’d ever put fish into your aquarium and then assume they could take care of themselves from there. You have to give your plants love too.

It’s not easy though. Growing live plants in your freshwater aquarium can be tricky because you have to strike the right balance with the nutrients these plants need to thrive. Too much of a certain nutrient can cause your plants to suffer. Too little of a certain nutrient can cause it’s own problems. People struggle with this every day, but fortunately it’s possible to troubleshoot. We’ve all been in your shoes and know how tricky it can be to figure this stuff out. That’s why we’ve put together this handy list to help you grow plants in your aquarium and watch them thrive. If you are having trouble with your aquarium plants, here are a few of the most common problems that you may encounter and how to deal with them.

Diagnosing Problems with Live Plants

Without the right nutrients, your live plants might lose their color or fail to grow at the proper rate. Here’s a diagnosis guide for common problems with live aquarium plants:

  1. Slow Growth: It’s important to remember that plants need three things to grow properly: nutrients, lighting, and carbon dioxide (CO2). So, if your plants aren’t growing quickly enough – or if the leaves are smaller than they should be at a certain point in their lifecycle– it may be due to poor lighting, a lack of nutrients in the water, or a carbon dioxide deficiency. It’s almost always one of those three problems. So, your first step in resolving the problem of slow-growing plants will be to figure out which of these three factors is out of balance. It might be that one element needs tweaking. Or you might even realize that more than one of these issues is to blame. For example, plants need carbon dioxide in order to grow. This is a vital part of their respiration process and it gets converted into oxygen as a product of photosynthesis. To increase the CO2 levels in your aquarium, you may need to reduce aeration to prevent CO2 loss. You can also try using a CO2 injector to increase CO2 levels. The lighting in the tank should also be adequate, based on the size of the tank. This is a little trickier to identify, so do thorough research to find uncover any potential lighting problems. Finally, in terms of nutrients, you can always apply some fertilizer to help your plants grow. Sometimes the simple solutions are the best ones.
  2. Yellowing of Leaves: Most live plants are green in color, so if they start turning yellow it is probably an indication of a problem. One possible cause of yellowing leaves is that there is far too little light in your aquarium. Try using a full-spectrum bulb that provides 3 to 5 watts of light per gallon of tank volume to help solve this problem. If it is only the edges of your plant’s leaves that are yellowing, it might be an indication of potassium deficiency. Fertilization is the best way to remedy this issue. So make sure to have some fertilizer on hand.
  3. Brown or Black Leaves: Aquarium plants need a few nutrients to be properly balanced in order for them to grow beautifully. This will also help prevent problems like brown or black leaves. Those crucial nutrients include potassium, phosphorus, and nitrogen. If you notice that the leaves on your plants are looking a little brown or black, there might actually be dark algae growing on them. What can you do to help restore the look of your plants? Well, if the leaves of your live plants start to turn brown or black and die, it might be an indication of excess phosphate levels in the tank. Or it could be an excess of nitrates that may have caused this problem. The best thing to do is to perform a large water change to improve water quality in your tank. After you improve water quality, keep up with weekly water changes to prevent the problem from happening again. All too often aquarium owners will think that they can leave water in their tank forever. That is absolutely not the case. That water needs to be changed regularly to keep your fish and your plants healthy.
  4. Holes in Leaves: When small holes start to develop in the leaves and those leaves start to break down, it is probably due to Cryptocoryne Rot. The cause of this disease is unknown, but excess nitrate is quite often a factor. Poor water quality and insufficient nutrients are relevant to this issue as well. So, the best way to remedy this problem is to perform a large water change and also to vacuum your gravel to remove excess wastes.
  5. Brittle Leaves: If the leaves of your live plants start to turn yellow and brittle, it may be due to an iron deficiency. It might also signal a potassium deficiency or a pH level that’s too high. To remedy this problem, you always can try fertilizing your substrate with an iron-rich fertilizer. Reducing the carbonate hardness of your tank water might help as well.
  6. Spindly Growth: If plants that normally grow thick stems seem thin. Of if leaves start to display weak, spindly growth, it might be a sign of inadequate lighting. The light bulbs might be too old, the bulbs might produce the wrong spectrum of lighting, or you might not be leaving the lights on for long enough. Adding more lighting, installing full spectrum light bulbs, and replacing old bulbs will remedy the problem. Monitoring your lights is crucial in maintaining healthy plants.
  7. Growth Stoppage: If your plants cease to grow and eventually start to die, it may be because the water temperature in your tank is too low. The only way to remedy the problem is to replace your heater or to add another one if the one you have isn’t sufficient to heat a tank of the size you have. That tank should maintain a consistently warm temperature if you want your plants to thrive.

Figuring Out Nutrient Deficiencies: Closely Observe the Leaves

Like all life, plants (including those that live in your aquarium) need to have access to the right balance of nutrients in order to grow beautifully and to thrive for a long stretch of time. Deficiencies in key nutrients can lead to a host of problems, so preventing imbalances before they occur can help you save time, and help you avoid unnecessary stress. You need to keep these plants well fed if you want them to be healthy. You need to think of them as your mute green children and make sure that they never starve.

A magnesium deficiency or a potassium deficiency might cause older leaves to develop unsightly yellow spotting. The difference, though, is that the veins in the leaves will remain green if there is a magnesium deficiency. Whereas new growth will be yellow along the edges if there is any sort of potassium deficiency.

Also, if there are yellow spots showing up on the tips, margins, and veins of your leaves, there might be a zinc deficiency. On the other hand, if there is a nitrogen deficiency, you might notice the leaves on the plants are turning red or yellow. Finally, if the leaves are turning yellow to white, there might be a deficiency of iron in the water. Pay careful attention to the color of your plant’s leaves and feed them nutrients accordingly.

It’s pretty clear that the symptoms of various nutrient deficiencies in aquarium plants are quite similar, so diagnosing the problem just by looking at your plants can be challenging. Here are a few things to look for to make it easier to figure out what’s going wrong with your plants (remember, this is just a rough guide. You will have to experiment until you discover exactly what your plants need):

  • Smaller than normal new growth that’s white or yellow: This means that your plants have a serious nitrogen deficiency.
  • Older leaves that show dead patches and yellowing, leaves that die and fall quickly: This means that your plants have a phosphate deficiency.
  • New growth that is twisted and pale: This means that your plants have a calcium deficiency.
  • Lighter color on older leaves, along with dark veins: This means that your plants have a magnesium deficiency.
  • Leaves with yellow edges and holes: This means that your plants have a potassium deficiency.
  • Older leaves turning yellow and dying: This means that your plants have an early nitrogen deficiency.
  • Older leaves that show yellowing and greenish veins: This means that your plants have an iron deficiency.

Using the tips above, you should be able to get a pretty good idea of what’s going on in your tank and how it is affecting your aquarium plants. If water quality is the issue, performing a large water change may be all you need. If it’s a nutritional deficiency, however, you might need to add fertilizer or treat the tank with the missing nutrient. If you can’t quite figure out what’s wrong, a broad-spectrum live plant supplement might help.

Here are our top picks for the best aquarium plant supplements:

  1. API Root Tabs: If you’re not quite sure what’s wrong with your aquarium plants, adding some fertilizer might solve the problem. These root tabs promote strong root development and contain all of the essential nutrients your live plants need to grow strong.
  2. API Leaf Zone Aquarium Plant Fertilizer: Packed with essential nutrients, this aquarium plant fertilizer offers rapid absorption, nourishing roots, stems, and leaves. This fertilizer contains carbon for plant growth and potassium to aid photosynthesis, helping your aquarium plants achieve optimal growth and healthy color.
  3. Fluval Plant Micro Nutrients Supplement: This supplement replenishes essential nutrients to support healthy plant growth and vibrant color. Enriched with iron and fortified with vitamin B, this supplement strengthens aquarium plants to promote growth and long-term vibrancy.
  4. Dennerle Plant-Elixir Universal Fertilizer: See your aquarium plants flourish with this universal aquarium plant fertilizer. Enriched with key minerals, trace elements, and essential nutrients, this fertilizer has everything your plants need to maximize growth and development.
  5. Reeflowers AquaPlants Nitrate Solution I: This water treatment for aquarium plants is designed to boost nitrogen levels to support healthy plant growth and development. By increasing nitrogen levels, this treatment increases the growth rate of aquarium plants and supports chlorophyll production.
  6. Kent Marine Iron & Manganese Freshwater Plant Supplement : Stimulate the growth of freshwater aquarium plants with this iron and manganese supplement. This treatment boosts potassium, manganese, and iron levels to ensure optimal plant growth while supporting life of macroalgae which act as natural filters to support water quality.
  7. Reeflowers AquaPlants Phosphate Solution II: Formulated to improve root growth, promote flowering, and aid seed production, this aquarium plant supplement boosts phosphorus levels while eliminating nitrate deficiencies. This supplement promotes healthy root growth for long-term health and vibrancy.
  8. API Leaf Zone Plant Treatment – Aquarium plants require a variety of nutrients to sustain proper growth and this liquid treatment contains everything they need. Simply dose the entire tank with 5ml per gallon and watch your plants start to grow well once more.
  9. Dennerle Carbo Elixier Bio Aquarium Plant Fertilizer: This liquid carbon fertilizer is formulated with natural ingredients to accelerate plant growth, ensuring lush, long-lasting foliage. Ideal for all types of freshwater aquarium plants, this fertilizer will have your plants looking healthier and more vibrant than ever.

Cultivating a tank full of thriving aquatic plants can be a challenge, but it is definitely worth the effort. There’s nothing like gazing into your aquarium and getting lost in a lush underwater forest. If your plants start to develop problems, follow the tips in this guide and use our recommended products to restore them back to health. Being a plant parent is never easy, but the rewards are oh-so worth it!

Kate Barrington
Kate Barrington

Kate Barrington is the loving owner of two cats (Bagel and Munchkin) and a noisy herd of guinea pigs. Having grown up with golden retrievers, Kate has a great deal of experience with dogs but labels herself a lover of all pets. Having received a Bachelor's degree in English, Kate has combined her love for pets and her passion for writing to create her own freelance writing business, specializing in the pet niche.

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