If you’re looking to set up your first planted aquarium, you might have heard that you need to dose fertilizers to keep aquatic plants healthy. A quick look into the world of anything that’s not a low-tech, low-light aquarium with easy plants can be pretty intimidating, though. Where to start?!
To make things easier, we’ve summarized all the basics of aquarium plant fertilization, different fertilizer types and dosing schedules. Keep reading to find out everything you need to know to provide your plants with the nutrients they need!
Why Should I Use Planted Aquarium Fertilizer?
We’re not going to pretend that all planted aquariums always need to be on a tight fertilizing schedule for any chance of success.
Some undemanding plants get by quite well on just the natural ‘fertilizers’ that fish and other aquarium inhabitants produce. The truth is, though, that without using fertilizers your planted tank likely just won’t be the same.
If you’re looking to grow aquarium plants successfully and would like to understand why fertilizers are a rather essential part of this, simply keep in mind that there are three main factors that influence your plants’ ability to grow.
These factors are light, Co2 and, yes, fertilizer!
- Light – Plants need light in order to be able to photosynthesize and grow. Some aquarium plants can get by with very little light, while many others need special lighting systems to really thrive. However, blasting your tank with expensive LEDs is not going to give you any good results without…
- Co2 – That’s because without this essential nutrient, your plants can’t actually do anything with all the light that’s provided to them. Algae will take over instead, which can result in massive blooms. The Co2 that’s naturally released won’t cut it for many of the advanced plants, so you’ll need to set up a system to supplement it. The combination of good lights and a source of Co2 can result in explosive plant growth, but only if you also provide…
- Fertilizer – Plants require a number of substances to grow as they’re supposed to. We’ll tell you which in the next section (‘Micro VS macro’). For now, just keep in mind that without these substances, providing light and Co2 is just not really useful. Your plants can’t grow properly and will produce thin, spindly stems with pale and brittle leaves. Eventually they will likely die off.
Macro vs. Micronutrients – The Secret to Healthy Aquarium Plants
There is not one single mineral element that can provide plants with everything they need to grow successfully. There are actually quite a few. Some elements are required in relatively large amounts, so we refer to them as macronutrients. Others are only needed in trace amounts: they are micronutrients. So which elements are we talking about here?
Nitrogen, Phosphate and Potassium (also often collectively referred to as NPK). These are the most important components of aquarium plant fertilizers because larger quantities are needed. Other macronutrients include Calcium, Magnesium and Sulfur, but with the exception of Magnesium these are often not too important since they are already present in our water.
Iron, Chloride, Copper, Manganese, Molybdenum, Zinc, Cobalt, Nickel and Boron are some of the mineral micronutrients our plants need in small amounts to thrive. Although these elements are present in our tap water, plants will eventually deplete them and become ‘hungry’, meaning we’ll have to dose manually to make sure they do well.
Types of Aquarium Plant Fertilizers
In most cases you’ll encounter three different ways to provide your plants with their much-needed ‘food’ in your local aquarium store.
Additionally, you can give the DIY route a shot: it’s can be cheaper than buying liquid fertilizers, but is definitely a lot more work
Aquarium plants have two ways of absorbing nutrients.
Uptake happens through their roots and through their leaves. Most plants have evolved in such a way that their roots are responsible for the majority of nutrient uptake, just like with terrestrial plants. Others, though, rely entirely on their leaves because their roots are only meant to anchor the plant.
Aquarium plant fertilizer is usually either meant for root feeding or leaf feeding, not both.
Let’s have a quick look at the different aquarium plant fertilizer types out there, as well as some of their (dis)advantages.
Liquid Aquarium Fertilizers
- CARBON PRODUCTION: All plants require a source of carbon, and Flourish Excel is a great and convenient source of bioavailable organic carbon.
- IRON PRODUCTION: Flourish Excel also possesses iron reducing properties, thus promoting the ferrous state of iron (Fe+2), which is more easily utilized by plants than ferric iron (Fe+3).
- PHOTOSYNTHESIS: Plants must produce longer chain carbon compounds (photosynthetic intermediates). By dosing with Flourish Excel you bypass the involvement of chain carbon compounds, and introduce the already finished, structurally similar compounds.
To provide plants with nutrients by means of leaf uptake, you can use one of the many liquid fertilizer brands out there. This is a popular option among aquarium plant growers because of the ease of use.
More or less all you have to do is measure out the correct amount and pour it into your tank. Although liquid fertilizers can get a little pricey and need to be dosed regularly they’re one of our favorite options because they supply everything a plant needs to grow properly.
For plants like Java fern, Anubias and floaters a liquid fertilizer is the only option, as they don’t absorb nutrients through their roots.
We recommend Seachem Flourish – it is tried and proven over many years to help keep plants healthy and stable!
- Complete substrate for freshwater planted aquariums
- Contains major and minor trace elements to nourish aquarium plants
- Substrate encourages healthy plant root growth
A great way to provide your aquarium plants with the required nutrients is to use a substrate that comes pre-packed with everything they need (such as Eco Complete shown above). We don’t mean dirt here, but actual gravel that you can use as the main substrate for your aquarium.
This is an easy option since you don’t have to cap the substrate with sand as would be needed when using dirt, but it does have a major downside.
Because plants gradually use up the nutrients in the fertilized substrate, it will eventually deplete. Although it still works just fine as substrate after being depleted, you’ll have to switch to dosing liquid fertilizer, using fertilizer tabs or changing out all of your substrate once this happens.
Aquarium Fertilizer Tabs
- GROWTH TREATMENT: Seachem Flourish Tabs are growth stimulating tablets for plant roots which contain essential trace elements, amino acids, and vitamins.
- VITAMINS: Seachem Flourish Tabs are rich in iron, manganese, magnesium, calcium, potassium, inositol, choline B12, biotin, and other factors that have been determined to be beneficial to aquatic plant roots.
- NUTRIENTS: When inserted into the gravel, Seachem Flourish Tabs provide direct, time-released fertilization to the plants' root zone. Nutrients are slowly made available through enzymatic action of the plants' roots on the tabs.
Nutrient-loaded substrates are not the only way to provide your plants with fertilizer that can be absorbed through the roots. You can also manually add time-release fertilizer every once in a while in the form of small premade tablets usually referred to as root tabs.
These are probably the easiest option out there when it comes to aquarium plant fertilizer, as all you need to do is stick a tab into the substrate near your plants’ roots. One tab actually lasts quite a while!
That being said, the usefulness of many commercial root tabs is debated since they don’t usually contain all of the nutrients your plants need. Still, we like using then and they definitely help in giving your plants as many ways to absorb nutrients as possible.
Yet another frequently used way to provide aquatic plants with extra nutrients through their roots is dirt. If you’d like to go this route you can use specially formulated dirt for aquarium use, but you could also consider going for pond plant compost or even some types of regular potting soil.
Like the fertilized substrates mentioned above, dirt is a great way to give your plants a real boost. They’ll have all the nutrients they need at their disposal.
That being said, dirt seems to have gone ‘out of fashion’, as a lot of aquarists see it as unnecessary work and messy when disturbed.
If you’d like to try using dirt in your planted aquarium, make sure to cap it with mesh and then a layer of sand to prevent it from ending up all over the tank.
DIY Aquarium Plant Fertilizers
There are many commercial aquarium plant fertilizing products out there, most of which work perfectly well. They can be on the pricey side sometimes, though, which doesn’t exactly come in handy if you’re trying to maintain your aquarium on a budget.
If you’re DIY savvy you can consider making your own aquarium plant fertilizing products. Although it’s definitely not the most time efficient option, it will usually work just as well as commercial fertilizer.
DIY Root Tabs
DIY Root Tabs are very easy to make. All you’ll need are aquarium-safe time-release fertilizer grains and some gelatin pill caps. Simply place the grains into the caps, close them up and push the finished product into the substrate near plants that you think would benefit from the extra food.
DIY Liquid Fertilizer
DIY liquid aquarium fertilizer is another popularly used option.
All liquid aquarium plant fertilizers are essentially made from the same dry mineral salts dissolved in liquid, which means if you can acquire this base you can make the product yourself.
Tailoring the recipe to your own plants’ needs is a great way to ensure lush growth and much more economical, but do keep in mind that it can be a bit of a struggle to find and measure out the ingredients you need.
How to Dose Aquarium Fertilizer
If you’re using liquid aquarium plant fertilizers, it can be a bit of a hassle to figure out exactly how much to dose. Although commercial fertilizers generally list a recommended amount of product per dosing, it’s a good idea to not just blindly go off that. This is mainly because plants’ needs can vary greatly depending on the circumstances.
For example, if you’re just starting out with dosing, they might absorb greater amounts in the first few weeks to store away.
If your tank is more heavily stocked with fish the plants will need less. If you do very frequent water changes they’ll need more.
Measuring is the only way to really know what’s going on in the tank. Although you’ll get by with just following the instruction guidelines in many cases, it can really help to set up your own dosing schedule.
There are many different fertilizer dosing methods out there, all of them with their own philosophy and (dis)advantages. Which one will work best for your tank depends entirely on your own goals and preferences; if you’re not sure, just do some research and try different styles.
Keep in mind that you don’t have to follow one dosing method’s instructions to the comma. No two aquariums are the same and it’s best to simply go by what you see happening in yours.
We’ll discuss a few of the most popular aquarium fertilizer dosing methods below.
Probably the most popular dosing method around today is Estimative Index, also known as EI. It was coined by Tom Barr and its basic philosophy is that if we overdose nutrients, our plants will always do well.
This means not just fertilizer, but light and Co2 as well.Not all aquariums are suitable for the EI method, but if you’re looking to set up a high-tech aquascape with very lush planting, it might be just right for you.
Remember that you’ll have to pull out the pruning scissors on a regular basis when using EI, and you’ll have to get the balance in nutrients just right to prevent algae from taking advantage. A large water change is needed weekly to remove excess nutrients.
This method relies not just on dosing fertilizer into the water column, but supposes you’ll be using an enriched substrate as well. It was developed by Aqua Design Amano (ADA) as a means of instructing aquarists on how to use their line of liquid fertilizers and fertilized substrates.
With the ADA method, you dose limited liquid fertilizers, which works because the plants can rely on the substrate for additional nutrients. This is said to help prevent algae explosions. ADA works very well if you don’t mind slower growth rates and a more clean, less ‘jungly’ feel.
Perpetual Preservation System – This dosing method is, according to its creator, is based on the fact that each aquarium is unique and that there is no one-size-fits-all.
However, that doesn’t mean you need to be stuck testing, maintaining and tweaking constantly. It involves a specific DIY method of creating your own fertilizer and dosing according to the PPS system, which can be found here.
Poor Man’s Dosing Drops – The PMDD method relies on the philosophy that restricting phosphate means restricting algae growth, which is something any aquarist desires.
The original method is now considered outdated, because it’s been proven that your plants do really need those phosphates to thrive.
That being said, some aquarists still use the PMDD method, especially on low-light tanks that can benefit from the ratios provided by the schedule. They just make some modifications to ensure things run smoothly, such as adding a little extra phosphate.
Final Tips to Keep in Mind
All the above taken together might lead beginning aquarists to think that running an aquarium with more demanding plants that need to be fertilized is going to be a nightmare. So many products, so many methods and so many factors to keep in mind?!
We’d like to assure any aspiring aquascapers that although there’s a lot of information to take in on this topic, the best way is to just start. Simply following the instructions listed on your preferred brand of aquarium plant fertilizer is already going to lead to much better results than not dosing at all.
Once you feel ready, you can consider reading up on the different dosing schedules and figure out which best matches the type of aquarium you’d like to own (high-tech jungle? Minimalist? Low-light? Low-maintenance?).
Don’t worry about getting things exactly right, just focus on getting them right for your tank.
Lastly, remember that although all aquariums are different, the key to successful plant growth is balance. As we discussed at the start of this article, it’s crucial that your light, Co2 and fertilizer levels are balanced to prevent algae growth and unhealthy plants. As long as this rule is kept in mind, achieving aquascape success should be no issue!