If you have a planted aquarium, or even just a fish tank that also contains plants, you are probably wondering whether or not you need fertilizer to sustain those plants. We personally prefer using liquid fertilizer, as it tends to work the best, so this is what we are here to talk about today.
Chances are that your plants will need fertilizer, so you may as well make sure that you get the best liquid fertilizer for aquarium plants (this is our top pick).
Here Are Our 3 Favorite Ferilizer Picks
We take a look at why plants need fertilizer, if it is safe for fish, how to fertilize an aquarium naturally, plus we have put together our top liquid fertilizers picks for aquarium plants, let’s first quickly look at our top pick;
Best Liquid Fertilizer For Aquarium Plants: Our Pick
If you want to know what the best plant fertilizer is then we would recommend taking a look at this below option. Thrive All In One Liquid Fertilizer is our top pick for many reasons, let's take a closer look;
Thrive All In One Liquid Fertilizer
The reason why we like this option so much is because it is an all in one solution. All you need is this one single bottle to fully fertilize any aquarium plants. You don’t need a bunch of containers and liquids for the different substances, which is always nice.
On that same note, this bottle of Thrive All In One Liquid contains enough liquid to treat a full 2500 gallons of aquarium water. In other words, this stuff is super concentrated and powerful, which means that a little goes a long way.
We do also like that as long as you follow the proper dosing instructions, Thrive All In One is perfectly safe to use when fish are in the water. It won’t kill or harm them as long as you follow the directions, which is really important no doubt.
This stuff contains tons of different macro and micro nutrients, all of which are needed for the healthy growth of aquarium plants. It contains tons of nitrogen, phosphorus, potassium, and about a dozen other beneficial nutrients too.
In our opinion, Thrive Fertilizer is one of the the best option around. Heck, you barely even have to measure anything. The top is like a liquid hand soap pump, and all you need to do is pump the lid once to release 2 ml of fertilizer, which should be more than enough for most planted tanks.
Dosing is made easy thanks to the pump lid, a beneficial aspect which many other liquid fertilizer bottles don’t seem to understand.
- Tons of nutrients.
- Over 16 different beneficial substances.
- Safe for fish.
- Easy to dose.
- Can be stored at room temperature.
- Super concentrated – a little goes a long way.
- A great all in one solution.
- Can cause nitrate spikes – increased need for biological filtration or the right plants can help.
Do Aquarium Plants Need Fertilizer?
More or less, the answer to this question is yes, aquarium plants usually always need some kind of fertilizer. Now, this is not always the case, but more often than not, it is the case. All plants need 3 important substances to grow big and strong.
These include nitrogen, phosphorus, and potassium. The point here is that there is usually not enough of any of those substances in any aquarium to fully sustain plant life.
Now, if you have a smaller tank with 1 plant, you probably won’t need any fertilizer, but tanks with large bio loads of plants definitely need it. There simply are not enough nutrients in the water to sustain a large amount of plant life.
If you have a lot of rooted plants, they will get most of their nutrients from the substrate you have them planted in. Here, if you have good aquarium substrate, such as a nutrient rich aquarium soil, you probably won’t need fertilizer.
Good aquarium soil will have enough nutrients contained in it to support quite a few plants for many months. However, these nutrients will be used up at some point, so eventually you will need fertilizer. At the same time, if you are using something like gravel for substrate, you will also need fertilizer as gravel has no nutritional benefits for plants.
Finally, for floating plants, you will need to add liquid fertilizer into the water, as they have no roots planted in substrate. Floating plants absorb all of their nutrients from the water column, so you need to make sure that the water column has all of the nutrients in it to sustain healthy plant growth and development.
So, the main takeaway here is that mostly all aquarium plants will need some kind of fertilizer at one point or another.
5 Aquarium Plant Fertilizer Reviews
If for whatever reason, the above option of liquid fertilizer, our own number one pick, does not suit you and your needs, you can always take a look at these 5 other options that we also really like.
1. Seachem Flourish Excel
While Seachem Flourish is not exactly our number one choice of liquid plant fertilizer, it does have a specific benefit over the number one choice, the Thrive All In One Fertilizer.
Our number one choice was bad in terms of nitrate content and nitrate production, which is bad for fish. Well, Seachem Flourish Excel does not contain any nitrates, thus eliminating this problem all together.
On a side note, another neat aspect of Seachem Flourish is that it kills algae. We don’t want to get into the science stuff here, but this stuff will kill algae, which helps make your aquarium look nicer, plus it leaves more nutrients and other beneficial substances in the water for your plants to use.
The main ingredient here is organic carbon, something that all plants need and usually get from carbon dioxide. However, if you don’t have enough CO2 in your tank, this stuff can be very helpful.
Now, we should also make clear that Seachem Flourish is designed to reduce iron in the water, but also to increase the amount of ferrous iron in the water, a type of iron which plants need to survive and is much easier for them to absorb than regular iron.
Now, with all that being said, Seachem Flourish does not contain any phosphorus, potassium, or nitrogen, but it does have other beneficial ingredients, mainly the organic carbon.
- Promotes ferrous state of iron.
- Lots of organic carbon.
- Good supplement if you have low CO2.
- Kills algae.
- Easy to dose and easy to use.
- Fairly concentrated.
- Safe to use with fish.
- Does not actually contain any potassium, phosphorus, or nitrogen.
2. NilocG Aquarium Liquid Fertilizer
Yet another good option to go with NilocG Aquarium Liquid Fertilizer is actually one of our personal favorites. This stuff actually comes in 2 separate bottles, which together contain enough nutrients to treat around 2500 gallons of aquarium water.
In other words, NilocG Aquarium Liquid Fertilizer is extremely concentrated, which is useful because it does not take very much to get the job done. Each bottle contains 500 ml of liquid fertilizer.
To be clear, one of the bottles contains all of the macro nutrients (the big players), ones such as nitrogen, phosphorus, and potassium. The other bottle contains a bunch of micro nutrients (the less crucial, bit still important substances) such as magnesium, carbon, and other beneficial natural elements for plant growth.
All in all, there are over a dozen different nutrients divided up between the two bottles, all of which will definitely help with plant growth.
For proper dosing, you should use the nutrients alternatively, using the micro nutrients every second day and using the macro nutrients on the days in between using the micro nutrients.
You should do a weekly 50% water change if you plan on using NilocG Aquarium Liquid Fertilizer regularly, but that is pretty much the only downside to this particular liquid aquarium plant fertilizer.
- Very concentrated – a little goes a long way.
- Easy to dose.
- Tons of macro and micro nutrients.
- Safe to use with fish.
- Good supplement for low carbon levels.
- Great all in one solution.
- Requires increased water changes.
3. API Leaf Zone
This next option on our list, API Leaf Zone, is a great option if you don’t have enough iron and potassium in your tank to sustain healthy plant growth. It contains quite a lot of both of those substances, so there is no problem there.
Both are required by plants for development, so that is all good. However, what we do need to mention here is that API Leaf Zone does not contain any other nutrients for your plants, and that includes ones like nitrogen and phosphorus.
Therefore, API Leaf Zone is a good option if you need more iron and potassium, but not if you need a good all in one fertilizer with all of the necessary macro and micro nutrients needed by your aquarium plants.
All of that being said, this liquid aquarium plant fertilizer is specially formulated so that your plants absorb it rapidly, thus expediting the process of nutrient absorption.
Moreover, one single bottle is fairly concentrated and will last for quite a while. 5 ml is enough for 10 gallons of water and the bottle contains a full 16 ounces of liquid fertilizer. While it is not a great all in one solution for plant health, it does have some beneficial properties no doubt.
- Easy to dose.
- Very concentrated.
- Lots of iron for plants.
- Lots of potassium for plants.
- Safe to use with fish.
- No nitrogen or phosphorus.
4. Brightwell Aquatics Plant Care
Yet another great option to go with, Brightwell Aquatics Plant Care contains all of the nutrients your plants need to survive. It is an awesome all in one solution that contains 14 different macro and micro nutrients, including all of the most important ones that aquarium plants need to survive, such as potassium, nitrogen, and phosphorus too.
We do really like the fact that this one little bottle has everything plants need for healthy development. There is also the fact that it is safe to use with fish.
What is pretty cool about Brightwell Plant Care is that it contains trace amounts of iodine, which allows shrimp and crustaceans to molt much easier. It’s a good option to go with in order to fertilize plants as well as to establish good and beneficial water parameters.
We do also like how Aquatics Plant Care is fairly concentrated, which means that a single bottle should last you for many months to come. Oh, and dosing is made fairly easy with this stuff, which is always nice.
- Contains all necessary macro nutrients.
- Contains tons of micro nutrients.
- Iodine for crustaceans.
- Easy to use.
- Easy dosing.
- Fairly concentrated and economically efficient.
- Safe to use with fish.
5. Sungrow Plant Fertilizer
To get it right out of the way, this Sungrow Plant Fertilizer is perfectly safe to use around plants. Now, one of the really cool aspects of this stuff is that you can actually apply it straight to substrate in order to help seeds germinate much faster.
That is not something which many liquid fertilizers can do. What is also neat is that you can use Sungrow Plant Fertilizer for pretty much anything including plants, veggies, your lawn, and of course for your aquarium plants too.
This is a really nice option to go with because it contains all of the necessary micro and macro nutrients needed to support aquatic plant life. It is not deficient in any of the main substances needed for plant growth.
Something else we like here is that Sungrow Plant Fertilizer is made from a very sustainable source, and therefore does not damage the environment. All in all, while it is not the number one best option out there, Sungrow Plant Fertilizer is still one of the better ones.
- Lots of macro nutrients.
- Tons of micro nutrients.
- Safe to use around fish.
- Multi purpose use.
- Made from sustainable sources.
- Helps seeds germinate faster.
- Dosing is not that easy.
- Can make water a bit cloudy.
How To Fertilize Aquarium Plants Naturally
If you do not want to use chemicals or buy bottles of liquid fertilizer to support your aquarium plants for whatever reason, you will need to find some way to provide them with the nutrients they need to survive.
If you are not a fan of bottled substances, there are some natural ways you can fertilize your aquarium plants. So, how do you fertilize aquarium plants the natural way? Luckily it is not all that hard.
One of the things you can do to ensure that there are lots of nutrients in the water for your aquarium plants is to have a good biological filtration unit and maybe even a bio media reactor.
Simply put, these biological filtration devices assist in the development of beneficial bacteria which serve to get rid of poisonous elements like ammonia and nitrites. Well, the bacterial process which breaks these things down actually helps create potassium, nitrogen, and phosphorus, or in other words, biological fertilizer.
Another thing that you can do in order to fertilize your aquarium plants the natural way is to make your own fertilizer powder. You can mix Epsom salt, salt peter, and potassium sulfate at a ratio of 3:2:1 respectively.
If you are wondering about dosing, about 1 teaspoon for every 10 gallons of aquarium water is ideal. Don’t add too much into the water at once however. You can also choose to add trace amounts of iron and zinc into the water to help sustain plants.
Commonly Asked Questions
Is Aquarium Plant Fertilizer Safe For Fish?
Yes, aquarium plant fertilizer is for the most part perfectly safe for your fish. There are some chemical plant fertilizers that are only intended for planted tanks, but these will usually be clearly labeled. A good organic or biological liquid fertilizer will not harm the fish in your tank.
Now, you do need to follow proper dosing instructions here, because adding way too much of it can have negative effects on your fish. However, for the most part, this stuff is perfectly safe to use when there are fish in the tank.
Should I fertilize my aquarium plants?
If you just have a couple or a few plants in a fish tank, along with a bunch of fish, then no, for the most part you aren’t going to need fertilizer, as the few plants in the tank will receive enough nutrients.
However, if you have a large and heavily planted tank, especially one with specialized, sensitive, and demanding plants, then yes, you will probably want to fertilize them in order to provide them with the nutrients they require to stay alive and to grow.
What nutrients do aquarium plants need?
The most common nutrients which aquarium plants require include nitrogen and phosphorous (most important) as well as potassium, iron, magnesium, manganese, and a few other less important ones too.
If you are looking to buy aquatic plant fertilizer, you want decent amounts of all the nutrients we just mentioned to be contained within. Many aquarium plants will also benefit from regular CO2 injections.
How often do you fertilize aquarium plants?
If you are using the best aquarium plant fertilizer than you can find, then you should be dosing your aquarium plants with fertilizer between 2 to 3 times per week.
If you have a lot of light in the tank, go for 3 times, and if you have less light, once or twice should do just fine. If you only have a couple of plants in a tank otherwise filled with fish, then never will probably do fine too.
Will plant fertilizer kill fish?
No, plant fertilizer will not kill fish, at least not directly. It’s not like dumping rat poison or cyanide into the tank. However, indirectly, yes, plant fertilizer can in some cases kill aquarium fish.
Plant fertilizer, due to what it contains, has the very real possibility of causing algae blooms. When that algae dies off and decomposes, it saps the oxygen right out of the water.
This lack of oxygen is therefore what can kill fish. That said, if you dump a whole bag of fertilizer into the tank, instead of a single teaspoon (or whatever the dosing directions are), then yes, you’ll probably kill the fish.
Should I get an all in one aquarium plant fertilizer?
If you are looking to save a bit of money, only want to deal with one product, and want a simple option, then yeah, all in one aquarium plant fertilizer is a perfectly fine option to keep in mind.
That being said, be careful that you get a fertilizer that has decent levels of all minerals, because more often than not, all in one options can be somewhat low quality. Just make sure to read the ingredients list and nutrient contents table so you know what you are getting.
As you can see, there is really not all that much that goes into fertilizing your plants. Just get yourself a good fertilizer (this is our top pick) with high ratings and make sure to follow the dosing instructions carefully.
However, as long as you find an option that is not toxic to fish and has the 3 main substances needed for plant growth, you should be just fine.