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Your aquarium is a tiny oasis for your pleasure and the happy thriving community of the unique combination of animals, fish, and plants that live there.

And that means you want every aspect of the environment to be healthy and helpful to your critters and your live plants.

One of the ways this can be enhanced is through the use of the best fish tank fertilizer.

Best Aquarium Plant Fertilizer Quick-Find Table

Image Product
  • Good for plants who take in nutrients via leaves and stems
  • Easy to use in almost any aquarium
  • Fast-acting
  • Good for plants who take in nutrients via leaves and stems
  • Easy to use in almost any aquarium
  • Fast-acting
  • Good for rooted plants
  • Complete formula for health freshwater plants
  • Incredibly easy to use – just install as substrate
  • Good for rooted plants
  • Complete formula for health freshwater plants
  • Incredibly easy to use – just install as substrate
  • Good for “multipurpose” nutrition for your plants
  • Slow release carbon compounds for steady plant growth
  • Doesn’t alter the pH balance of your tank
  • Good for “multipurpose” nutrition for your plants
  • Slow release carbon compounds for steady plant growth
  • Doesn’t alter the pH balance of your tank

Do Aquatic Plants Really Need Fertilizer?

Plants that we keep in our garden, flower beds, and indoors in pots all need fertilizers to help make sure they receive the nutrients they need to grow and flourish. But what about the ones we keep in our aquariums?

best aquarium plant fertilizer

Not every aquatic plant will need fertilizer, especially if you maintain the aquarium’s pH balance, provide suitable substrate and light, and there’s enough CO2 in the environment.

But the fertilizer can certainly help the plants in the middle of those requirements, and if you’re trying to restore some plants that may have experienced some neglect, the aquarium plant nutrients can especially be a life-giving help.

What Else Do You Need to Do for Healthy Planted Aquariums?

As mentioned above, your plants need more than just fertilizer to thrive. In fact, without these other elements, the fertilizer won’t do a lick of good.

Adequate Light

Aquatic plants, just like land plants, need adequate light to produce energy via photosynthesis. A broad spectrum LED light is your best bet for finding the right lighting setup for your planted aquarium

Sufficient CO2

Plants also need high enough CO2 levels to produce energy and growth via photosynthesis. Without this, your plants will be dead in the water. If you find your plants are not doing very well, you may well wish to invest in a CO2 system for your aquarium to help them out. 

The Proper pH Balance

For an aquarium to sustain fish and live plants, they need the right pH balance for utilizing essential nutrients. Typically, these levels need to be kept between 6.5 and 7.0 pH for optimal health and growth. Be sure to study up on specific levels for your plants and fish however, and regularly test to keep everything as it should be in there.

Before Adding Fertilizers to the Aquarium

Before you add in your plant fertilizer, be sure to check on the levels of CO2, pH, and light.

Make necessary adjustments to avoid any issues with overgrowth, algae bloom, et cetera, often caused by an imbalance of these essentials.

Types of Aquarium Plant Fertilizers

Aquarium plant fertilizers come in three basic forms: substrate, root tablets, and liquid. Each should only contain the micronutrients required by your aquarium.

The micronutrients required in aquariums include ones such as iron, zinc, boron, manganese, copper, molybdenum, and cobalt. These are what your plants are craving and why you use fertilizers.

The macronutrients – like potassium and calcium – are provided by the fish and plants you keep, so you don’t want any additional such in your fertilizers.

Substrate Fertilizers

Substrate fertilizers are the longer-lasting option of the two forms of aquarium plant food. They don’t have to be dosed, like liquids, so they are generally a lower maintenance option for aquarists. However, there’s no real difference otherwise, and the form of fertilizer used is completely a preference-based situation.

Liquid Fertilizers

Liquid fertilizer for aquarium plants must be dosed frequently, so it’s an easy to use product, but less convenient for anyone who needs a low maintenance aquarium. Aquarium liquid fertilizer is great for Java Moss, Java Ferns, Frogbits, and similar plants.

Root Tablets

The final type of aquarium plant fertilizer is root tablets. These are great for specific types of plants like Cryptocorynes and Amazon Swords. These tablets directly feed the roots – much like substrate fertilizers do – and are best for plants that need direct contact with their nutrient source.

Are Fish Tank Fertilizers Safe for Fish and Other Critters?

Most fertilizers are safe for most fish and critters. The key is looking carefully at the makeup of the specific fertilizer and verifying there aren’t any traces that can harm specific animals you’re keeping.

For example, I’ve seen a lot of folks discussing shrimp and copper in some of the forums. The tiniest trace of copper may be great for some plants and harmless to specific fish, but shrimp don’t seem to do well with copper and could become ill or die.

Before buying any fertilizer, study up on the specifics of your critters.

How to Choose the Right Aquarium Plant Fertilizer

There are a few specific things you’ll want to consider as you shop for the right fertilizers for your plants.

Understand the Nutrients

The key factor for all of your considerations, save one, comes out of the nutrients contained in the aquarium plant fertilizers that you’re considering working with.

The macronutrients, as mentioned above, should be limited, since your fish already provide most of them through the natural food cycle. But the nutrients you may see included are:

  • Nitrogen
  • Phosphorous
  • Potassium

Your plants do need these nutrients – and natural is always the best – but generally speaking, most aquariums produce enough of these macros naturally and don’t need extra. Be sure to avoid using planted tank fertilizer that has high concentrations of these macros.

The micronutrients, on the other hand, are what you’re looking to have included. These will vary somewhat based on the types of critters you keep, but you’re looking for any or all of the following:

  • Iron (Fe)
  • Manganese (Mn)
  • Chlorine (Cl)
  • Copper (Cu)
  • Boron (B)
  • Molybdenum (Mo)
  • Cobalt (Co)
  • Nickel (Ni)

These micronutrients are the ones that fish and other aquatic animals don’t naturally produce and release into the water for the plants. So, you’ll want an aquarium plant fertilizer safe for fish that includes most or all of these micronutrients.

tropical freshwater aquarium with fishes best aquarium plant fertilizer

Understand Your Fish and Plants’ Needs

Next, it’s important to research your specific plants and aquatic animals and fish and understand what they need and don’t need. You also need to understand how your aquatic plants feed – via root, water, or otherwise.

Some plants ingest the nutrients through their root systems. These are known as heavy root feeders. Some of these plants include sword plants and Cryptocorynes. Others absorb nutrients through their leaves and stems – i.e. via water. Some of these are Java Ferns and Java Moss. Others do a mix of both and do best with a combination of aquatic plant fertilizers for the best results.

Reviews of the Best Aquarium Fertilizers You’ll Find

There are a wide range of aquarium plant fertilizer options. But finding the best aquarium plant fertilizer can be tricky. Use the hints above, do a bit of study on your specific species, and look out for the right combination of qualities for your aquarium in the list below.

How We Chose the Aquatic Plant Fertilizers

After doing loads of research and study, we found a large number of options on the market. Some of these were great, and some not so much. So, we used special criteria to determine exactly which ones to suggest for your various aquatic plant fertilizer needs.

  • Well-trusted, reliable brands
  • High ratings from real-life users, verifying the long-term effects
  • Affordability
  • Ease of use
  • The right macro and micronutrient profiles

#1. Seachem Flourish Excel

Seachem Flourish Excel Bioavailable Carbon review

What We Loved

We love that the Seachem Flourish Excel is a very fast-acting aquarium plant fertilizer. You drip a capful of the product into the water and it kicks in quickly enough that you’ll see a difference in your plants within a few days.

Since certain plants – Anubias, Java Ferns, et cetera – can’t absorb through their roots, we love that this fertilizer is super easy to use and safe for your fish swimming around in it.

It’s a really popular option with aquarists – including myself – thanks to how easy it is to use. Most of us have enough trouble making the time to care for all the cleaning and other forms of maintenance for our aquariums, so having something to simple, quick, and easy to use on the next level of care for those gorgeous planted aquariums is extremely helpful.

We’ve also noticed and loved that this fertilizer helps the healthy plants and other forms of filtration to rebalance the tank and keep algae bloom down.

It’s not a cure all – certainly not a Round-Up of algae – but it can help with a little extra boost of balancing qualities your aquarium might otherwise be lacking.

Finally, and potentially most importantly, what we love about Seachem Excel is that it doesn’t contain those macronutrients that your aquarium doesn’t generally need more of. Some review sites complained about this, but since we want to reduce things like phosphorous and nitrogen – except in special cases – we think this makes it the absolute best choice out there.

What We Didn’t Love About Seachem Flourish Excel Bioavailable Carbon

The main thing we noticed with this one is that some folks have mentioned some issues with invertebrates dying once they started using the product.

Because of this, we’d recommend avoiding use if you keep snails, though the shrimp seem to do okay, despite the trace amounts of copper.

Our Verdict on Seachem Flourish Excel Bioavailable Carbon

If you’re keeping an aquarium with a variety of plants or just those who absorb nutrients through their stems and leaves, you need to look no further than Seachem Flourish Excel.

This liquid fertilizer is easy to use, provides a great micronutrient profile, doesn’t have the unnecessary macronutrients, and does a great, fast-acting job of boosting plant growth and health in your aquarium.

Plus, bonus, it helps to rebalance your tank and therefore reduces algae by a bit.

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#2. CaribSea Eco Complete

CaribSea Eco-Complete 20-Pound Planted Aquarium

What We Loved

If you want a low maintenance, easy to use aquarium fertilizer substrate, the Carib Sea Eco Complete Planted Black Aquarium Substrate is your best bet.

We love low maintenance – who has time for all the messiness of high-maintenance stuff? – and easy installation products, and this definitely meets those descriptors.

We love the fact that with this fertilizer, you don’t also need additional substrate layers of sand – though gravel may be good in some freshwater settings – so you have less work and material costs. Plus, the substrate doesn’t need replacing or refreshing very often, so you also save by using this.

This particular substrate is made of basaltic volcanic soil which naturally contains iron, calcium, potassium, sulfur, magnesium, and 25 other nutrients that can nourish your plants. It’s a mineralogically and biologically complete plant growth substrate, so you don’t need to add laterite and other products, as well.

We love that there are no artificial dyes or chemicals used to “create” the substrate, but that it’s an all-natural option for providing your plants with the food they need.

What We Didn’t Love

This definitely isn’t a good substrate for shrimp. Tanks without these little invertebrates do pretty well and the substrate is great for biological filtration.

It’s also not a great substrate for cories and other burrowing critters, as it’s a little bit sharp for bottom feeders.

Our Verdict on Carib Sea Eco Complete Planted Black Aquarium Substrate

Ultimately, using the Carib Sea Eco Complete Planted Black Aquarium Substrate is one of the easiest and lowest-maintenance ways to provide your root-feeding plants with loads of richness.

It’s easy to install and maintain, reasonably priced, and even attractive. Just be sure to avoid using with shrimp and burrowers, as they may not do so well in it, thanks for the shape of the particles.

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#3. API CO2 Booster

API CO2 BOOSTER Freshwater Aquarium Plant Treatment

What We Loved

First off, we love API, so we love the API CO2 Booster. This brand is well-established in the industry with a reputation of high-quality products that really do the trick. One of the biggest things in the fishkeeping game is using brands that are reliable, so API wins points automatically.

We love that when this is used correctly, your plants will thrive. It’s for freshwater aquariums only and should be dosed daily in the proper amounts using an eye-dropper. Within a couple of weeks, you’ll see improved growth and health.

We also love that this particular fertilizer takes a very direct approach on how it helps with the care of the plants. It injects carbon – or CO2 – into the water for a boost in the photosynthesis process. We’ve seen plants thicken and spread through use of this product.

Finally, we love that you can use this with a CO2 system or as a stand-alone plant-boosting product for a better, healthier aquarium. For those who can’t justify or don’t need a full on system, this is a great alternative.

What We Didn’t Love

One of the main issues we see with this one is that it can be difficult to decide how much to dose your aquarium with.

That’s a rather big deal – too much harms, too little has no effect.

Because of this, we recommend this for those who are able to do reasonably heavy research on their own aquarium set up and have long-term understanding of what helps and what hurts aquarium plants and their companion critters.

This is also a pretty potent, so it’s not great for small tanks. Use precaution if you put this into anything under 25 gallons.

Our Verdict on API CO2 Booster

All-in-all, the API CO2 Booster is a fantastic option for increased freshwater plant growth. It focuses on a particular area of need in the water – while others are usually more generalized – and adds an extra kick for that improved photosynthesis process.

Just use common sense, proper pre-cautions, and follow instructions carefully to avoid over or underproducing the CO2 you’re looking for in there.

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Some Popular Runners Up

The next several options are also extremely high-quality options for the various forms of aquarium plant fertilizer that you might need. For example, the API Leaf Zone vs Seachem Flourish selections are great choices that may just be better for your situation.

API Leaf Zone

API Leaf Zone is another great liquid fertilizer that’s extremely popular among hobbyists.

It promotes strong, colorful plant growth and only requires weekly dosing instead of daily, like many other varieties do.

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Seachem Flourish Root Tabs

Seachem Flourish is one of the most widely ranging line of planted aquarium fertilizers.

Each one has unique features and benefits that will help your plants thrive, but the root tabs are especially great for plants who require heavy concentrations of nourishment at the root base. 

Seachem Flourish dry aquarium fertilizer comes highly recommended by nearly everyone who uses them and is made by an extremely familiar and trusted brand.

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Thrive Fertilizer

For the best low-tech planted tank fertilizer, Thrive is your best option.

It comes in an incredibly easy to use hand pump situation, which makes it easier and better for beginners and busy folks to get it right.

And it works – it really works – so it’s an all-around great product.

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