Do Aquarium Plants Need Fertilizer?

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Many aquarists consider that adding plants to their aquarium creates additional problems that require additional solutions.

After all, they’re already dealing with the care and maintenance specifics of their fish and other aquarium life forms. They don’t need the fuss of having to care for live plants as well.

However, live plants are essential to a well-balanced aquatic environment. Caring for them isn’t that much different than caring for the fish, and the first thing that comes to mind is nutrition.

Do plants require fertilization, or can they self-sustain with little assistance on your part?

Let’s see!

Can Aquarium Plants Grow Without Fertilizer?

The most honest answer is – it depends. Most plants require external fertilization for the simple reason that they’re growing in a closed environment.

The aquarium creates a different setup than a natural, open environment, where there is free circulation of nutrients. Aquarium plants need additional fertilization since their available nutrients will eventually run out.

However, this is a general idea. When going into specifics, we observe that not all plants demand extra fertilization.

So, let’s look into the specific cases to determine which plants need fertilization and which don’t:

  • Sufficient organic matter – Plants feed on the phosphates resulting from dead organic matter. These include food residues and fish waste. If your aquarium is overpopulated or inhabited by professional poop producers (goldfish, am I right?), your plants may not require additional fertilization. We’ve mentioned goldfish because these fish are extensively used in aquaponics thanks to their ability to produce a lot of waste.
  • Nutrient-rich aquarium soil – Soil is the plant’s natural form of substrate and will contain all of the nutrients that your tank plant requires to grow. The soil will naturally have its downsides when talking about aquarium use, but it’s undeniably the best option for your plants. A high-end type of aquarium soil, combined with active waste-producing fish, will eliminate the need for fertilizer use.
  • Using inert substrates – Inert substrates define those types of substrates that pose no nutritional value. Gravel and sand are the best examples in this sense. Live plants cannot grow in sand or gravel without additional fertilization since these types of substrates are considered inert.

Once you’ve determined whether your plants need fertilization or not, you now need to figure out which type.

That’s because you also have floating plants to worry about, and these have no roots. So, you can provide them with your typical root tabs.

What Type of Fertilizer do You Need for Aquarium Plants?

The type of fertilizer to use depends on several factors, such as the plant’s needs, the plant’s type, the available substrate, other environmental conditions, etc.

To cut it short, plants need:

  • Macronutrients – Plants need these in larger quantities daily. They include nitrogen, phosphorus, and potassium as core nutrients.
  • Micronutrients – Manganese, boron, iron. These components are also vital for plant development.

When it comes to the fertilizer itself, you have several options available:

  • CO2 injections – These are very much optional and depend on the type of plants you have. Not all of them will require CO2 injections, but some will. You can tell that your plants require additional CO2 if they exhibit stunted growth, discoloration, or yellow leaves.
  • Root tabs – Root tabs are essential when using inert substrates like sand or gravel. These have no nutritional value, so root tabs will provide a steady production of nutrients meant to support your plants’ growth rate. How you use your root tabs depends on the plants themselves. Some will require one root tab per week, others will require one every 2 weeks, while others may need 2-3 per week. Larger plants will naturally require more nutrients overall. You only need to bury the root tabs in the substrate near your plants’ roots, and you’re good to go.
  • Liquid fertilizer – These are necessary for floating plants that lack any type of rooting system. These plants will extract their nutrients directly from the water stream.
  • Let nature handle it – We’ve already discussed this previously, and it refers to having plenty of fish producing a lot of waste. This is an easy way of providing your plants with all the nutrients they need in the long run.

A couple of things here. First, we should discuss the liquid fertilization problem. While liquid fertilizers are essential for floating plants, they can also promote algae growth when used in excess.

So, always stick to the recommended quantities to prevent that.

Secondly, relying on natural fish waste to fertilize your plants naturally is a double-edged sword. That’s because fish waste also feeds the colonies of ammonia-producing bacteria, and ammonia is deadly to all aquatic life.

So, you need to find a balance, perform regular water changes, and constantly monitor ammonia levels to make sure that the environment is properly cycled. The ideal ammonia value you’re looking for is 0.

How to Add Fertilizer to Planted Aquarium?

The actual fertilization process is relatively simple. If you’re using liquid fertilization, you simply pour the necessary amount straight into your aquarium water.

If you need root tabs, bury them in the substrate, around 2-3 inches from the plant’s roots.

But, if you have multiple aquarium plants, you will probably need to bury root tabs throughout the substrate, preferably 2-4 inches from each other.

This will optimize the dispersion area of the nutrients and provide all plants with adequate long-term nutrition.

Regarding the amount of fertilization to add, there’s no single value to consider. The amount of fertilizer to use varies based on your unique aquarium setup and specifics.

As general values, you need up to 25 mg per liter of nitrate, 10 mg per liter of potassium, up to 1 mg per liter of phosphate, and up to 10 mg per liter of magnesium.

Do Floating Aquarium Plants Need Fertilizer?

Yes, floating aquarium plants require fertilization since they get their nutrients from the water column itself. A form of liquid fertilization is necessary to provide your plants with optimal nutritional values.

Be careful about it, though. Your algae cultures will also appreciate the extra nutrients since excess liquid fertilizers have been linked to algae bloom in planted aquariums.

Aquarium algae aren’t necessarily bad when kept under control. They don’t alter the water’s chemistry and won’t impact your fish or plant population normally.

However, they tend to spread on all surfaces, including the plants themselves. This can cause them to restrict the plants’ access to sunlight, preventing photosynthesis, and killing the plants in the process.

Measure your liquid fertilizer precisely, and always keep an eye on the population of algae in your tank.

Is Aquarium Plant Fertilizer Safe for Fish?

Yes, plant fertilizers are generally safe for fish, with 2 major exceptions:

  1. Excesses are bad – Always stick to the recommended quantities and don’t go overboard with your fertilizer. The excess plant fertilizer will hurt the fish, causing more harm than good. It will also lead to excess algae formation and we’ve just discussed the dangers coming with that.
  2. Plant-specific fertilization – Some fertilizers are only meant for plant-only tanks; no fish, no crustaceans, no other aquatic lifeforms. Fortunately, these products are always labeled accordingly. So, don’t skip your read-the-label day.

Other than that, plant fertilizers shouldn’t cause any discomfort to your fish.

Can You Use Organic Vegetable Fertilizer for Aquarium Plants?

No, you should not. Organic vegetable fertilizers are more fitting for garden plants because the soil breaks down the product’s constituents more effectively.

Your garden is also an open system compared to the aquarium, and the plants are different as well.

Most vegetable fertilizers contain excess ammonia, which can spell disaster in a closed aquatic system. Not to mention, those types of fertilizers will fall short in terms of proper nutrient content.

This isn’t a problem for garden plants since they already get most of their nutrients from their surrounding environment.

Aquarium plants, however, function in a different setup. Even if you could use vegetable fertilizers, you would need to mineralize them properly beforehand.

So, skip these ones and opt for aquarium-only fertilizers instead.

Aquarium Plants That Don’t Require Fertilizer

Interestingly enough, not all aquarium plants require fertilization. That’s because they are more adaptable and can extract their nutrients from their environment more effectively.

Some of the most notable tank plants to consider in this sense include:

  • Asian Ambulia
  • Java moss
  • Java fern
  • Water wisteria
  • Hornwort
  • Water sprite, etc.

As you can see, we’ve already included some of the most popular aquarium plants here. As an important note – don’t take these ones for granted.

These plants are quite hardy and will get most of their nutrients on their own. However, they can experience nutritional deficiencies, depending on their environmental conditions.

So, always supervise your plants carefully for signs of nutritional deficiencies.

Aquarium Plants That Need Fertilizer

To cut it short, most aquarium plants require some type of fertilization. In essence, if you have plenty of fish producing a lot of poop, you don’t need as much fertilization as when you don’t.

Plants will usually inform you if they require nutrient supplementation, as they will experience hindered growth and change in coloring.

Make sure you inform yourself of nutritional deficiencies that your plants may exhibit. These will come with different symptoms, allowing you to identify precisely the type of nutrient your plant is lacking.

Conclusion

Aquarium plants require more fertilization than garden-grown or feral ones. That’s because their closed system doesn’t allow for the free circulation of nutrients.

So, your plant can’t get its nutrients anywhere else than what’s available in its habitat.

Naturally, fish-rich aquariums will provide plants with more nutrients, to begin with, reducing the need for fertilizer supplementation.

Overall, though, all plants require proper nutrition and sunlight to achieve their maximum potential.

avatar 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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