Is there a best all-in-one liquid fertilizer for the planted aquarium?

Jan 13

Is there a best all-in-one liquid fertilizer for the planted aquarium? In my opinion no. There's so many different brands and products out there and each one has its own set of pros and cons.

What it really boils down to are what are the demands of your tank? In this article, I'm going to break down some of the different fertilizers out there and how you can read the back of them to understand which one suits your tank best.

Watch the video for a little more detail.

Why is liquid fertilizer even important in the first place?

It’s no secret, plants need the proper nutrition to grow and there's three different categories when it comes to nutrition. First is structural second is macro third is micro.

The structural and macronutrients are really the building blocks of the plant they're actually the physical materials that the plants use to build so that they can grow. They account for roughly 95% of a plant’s dry weight.

Then there are micronutrients, which are found in a lot smaller percentage of the plants - roughly the remaining 5%. Those are important for regulating internal processes… but I’m not going to talk about chemical pathways today.

If you want to have really healthy plants you're going to want to give them both a good nutrient rich substrate and a liquid fertilizer. On average most aquarium plants will uptake about 80% of their nutrients from the soil and about 20% from the water column. This number is variable though.

If you have epiphyes like Bucephalandra, Anubius or Java ferns then that amount is almost 100% from the water column. Those plants don't set their roots in the substrate and they rely on having available nutrition in the water column.

Windelov Java fern growing out of a chunk of wood.

Nutrient deficiency

Let's say you have a really healthy planted tank and you stop using liquid fertilizers. Let's take a look at my 75 gallon to see what happened to some of my plants when I stopped using fertilizers after a year of usage.

It looks fairly healthy planted tank to me, but it's got a couple issues one of them being that the autodosing pump ran out of fertilizer. I don't know how long that was empty but I do know it was long enough to impact some of my plants. I used to have really healthy Bucephalandras. You can see this one is struggling a bit. It’s got some algae growth, brown/yellow leaves, and some holes forming in the leaves.

On the other hand, this giant Windelov Java fern shows no signs of nutrient deficiency. I guess that's one of the differences between a hearty plant and a sensitive plant. Bucephalandras aren't necessarily a difficult plant to keep but they are a little touchy. This Java Fern's almost bulletproof. You could throw it in a bucket leave it in your garage with a lid on the bucket for a few months and it would still be in good condition. I’ve done this many times.

When you start seeing signs like melting or yellowing on your sensitive plants, then you know hey something's likely going on with my fertilizers. It's a good idea to keep a few of these more sensitive plants in your tank because they're going to show signs of nutrient deficiency before your big ones do. And that's a good opportunity for you to solve those problems before they become big and impact your whole tank.

It’s the same with stem plants. Hygrophila angustifolia rubra is a super hearty plant that always does well. Contrastingly, Proserpinica palustris and Pogostemon erectus in this tank have taken a big hit from the lack of fertilizers. It’s completely my fault for not staying on top of the fertilizers.

Another reason why it's a really good idea to use Liquid Fertilizer is that it helps to extend the life of your soil or your substrate. If your plants are really hungry, they're going to deplete the nutrition from the soil quickly and you're going to end up having to put root tabs in there or even replace your soil altogether. Liquid fertilizer will really help you to extend the life of your soil maybe two or three times.

The 2 most common ways to dose

There's basically two different ways to dose your tank with liquid fertilizers. there's the all-in-one which is what I'm a fan of and then there's dosing each chemical element on its own.

Back in the day the technology wasn't around to combine all the chemical elements into one all-in-one fertilizer. When chemicals would mix they would cancel each other out (by binding to each other instead of dissolving in water) and some of the nutrients would become useless.

But these days that's not the case. You don't have to go out and buy a seperate calcium, iron, magnesium, zinc so on so forth… All that stuff you can just get it in one bottle!

I do think there's a big downside to using the dosing each chemical element separately unless you're an absolute expert. First off, it's hard to find test kits for everything and you run the risk of getting an algae bloom when you

overdose certain chemicals. Nitrogen for example is really linked to most types of algae. If you overdo iron you're likely gonna get a staghorn algae outbreak and then even if you underdo certain things like phosphorus you're prone to getting a green spot algae bloom.

So the all-in ones are really great because we know that you can kind of just look at the back of the bottle. There's instructions on how much to use. Everything should be balanced out if you pick a good brand and that means you're not going to have to go out and test a million different chemicals. In a little bit I'll go over how much you should be dosing.

Elements to look for in a fertilizer

So what chemicals should you be looking for in your liquid fertilizer? There's a bunch of different elements, chemicals or nutrients that you should be looking for and it's a pretty straightforward list I'll go over.

The structural elements for plants are carbon, hydrogen and oxygen. Plants get them from water and carbon dioxide. Even if you're not injecting CO2 in your tank it's still there and it's still absolutely essential for your plants to grow.

Then there are the macronutrients. Those are broken down into two categories the primary ones, which they need in a higher percentage. Those are nitrogen, phosphorus and potassium. The secondary ones are magnesium, calcium and sulfur.

The last category is micronutrients. This includes boron, zinc, manganese, iron copper, molybdenum and chlorine, though I’ve never seen chlorine listed in a fertilizer. It’s required in such low concentrations that plants likely obtain it from residuals in tap water. There are actually more micronutrients, but these are the essential ones for almost all plants, whether aquatic or terrestrial.

List of micro and macronutrients for plants.

You might notice that some companies sell macro and micronutrients separately. Usually the “macro” bottles include the primary macronutrients whereas the “micros” will include all of the secondary macronutrients. I use quotations, because technically the aquarium industry doesn’t adhere to the scientific or botanical definition of micro and macro nutrients. Since my background is in biology, I often notice and ignore these differences, but felt it was worth sharing this time.

So if you're looking for a good all-in-one liquid fertilizer essentially then it should have all of these elements that I've listed here. Realistically you might not find every single micronutrient listed and that's okay. Like I already mentioned, you probably won’t see chlorine but you should find all the other stuff.

A good all-in-one fertilizer absolutely needs to have all of the structural and macronutrients so if you're looking at some all-in-one fertilizer that doesn't include a lot of those nutrients then you should probably rethink whether that's a good option to use. These are all elements that are well proven to be essential for both terrestrial and aquatic plants!

Application

So how do you get these liquid fertilizers from the bottle into your tank? Well a lot of them come with a little pump. You can just pump it into the tank or you can buy a dosing pump and that's pretty convenient. It just runs on a timer and you have some little airline tubes that go from the fertilizer bottle, through the pump and up into your tank. You can set it to go off once a day, twice a day once every other day, three times a week… you can do whatever you want .

If you’re curious about the process for setting that up, check out this article.

Dosing quantities

One of the most important parts of this topic - how much all-in-one fertilizer to put in your tank?

There are instructions on the back of the bottle; they are basically what I use as a starting point. I start a little bit under what they recommend. Doses will usually be listed for high-tech or low tech-tanks. High-tech tanks need more and low-tech tanks will get less.

That's because intense light and CO2 is going to basically turbo charge your plants. It's going to their demand for nutrients because they’re growing so quickly.

If you're not using high levels of light or CO2 then your plants aren't going to be growing as quickly. As a result, they're not going to need as many nutrients. If you put a lot of nutrients into a low energy system like that it's going to result in algae and bad water quality, which is not good for your fish.

Look on the back of the bottle to figure out a good starting point. Oftentimes instructions will recommend dosing one to three times a week, but I prefer to do it daily. You can break it down by adding up the weekly dose and dividing by seven to figure out your daily dose.

Fertilizing throughout the week rather than dosing them heavy once or twice is better for your tank because it keeps nutrient levels lower on average. When there's a ton of nutrients that enter a tank all once you run the risk of getting an algae bloom.

Also by the end of the week when those nutrients are depleted algae is going to be competing with the plants for the remaining nutrients. If you fertilize small amounts daily, you’ll decrease the amount of algae that appears and give plants the edge.

When plants are healthy, they are better able to outcompete algae for those nutrients so there should never really be a period where your plants are hungry.

In order to find how much to add, take whatever the bottle says and start with a little bit under that level. Before dosing, test your nitrates. Then dose and test your nitrates after fifteen minutes or so to guarantee it’s mixed around. Then test your nitrates to see how much the fertilizers have raised it.

The following day, before you dose again, check to see where your nitrates are. Have your plants consumed a lot of nitrates? If your levels are down to zero, you can increase the fertilizer dose. If they haven’t moved much at all, decrease the levels. In general, I don’t like to see my nitrates get much above 20/30 PPM at any point during the process.

Obviously this is a lot of work, and we don’t want to be doing it forever. I usually only test off and on when setting up a new tank, then I ease off. After a while, you’ll get to know your tank pretty well and be able to pick up on the signs that it’s getting too much juice, or maybe not enough. Once you get to that point, congratulations and welcome to the club, you're an aquarium nerd!

Lean dosing vs EI

If plants are getting under 5 PPM nitrates that's called lean dosing. It’s popular for aquarists looking to bring out the red colors in their plants. On the opposite end, there's a method where you give your plants a lot more nutrients than they need - basically flush them with nutrients. That's called estimative indexing (EI) because we're just estimating that the plants need this much and blasting them with more.

Estimative indexing is a good idea if you have a really jungly tank with lots of stem plants and mature Java ferns. These types of tanks uptake a ton of nutrients. If you’re giving them a ton of nutrients, you’ll need to stay on top of water changes. It’s a good idea to do weekly 50% water changes when doing the EI approach.

Beyond looking at your nitrates you should be able to look at your plants and see if they look happy if your epiphytes are starting to get holes in them, that means they're not getting enough nutrients. If you're seeing algae forming on the edge of the leaves then that's a sign that there's either not enough or maybe even too much. If your glass is gunking up after a couple days, lay off the juice!

Looking at different brands and products

So how do you decide what the right brand and product are for you to use?

Well first of all, you should decide what your goal is. I've talked about micro and macro nutrients and you should think about how that relates to your tank.

If you have small fish that aren't producing much biowaste and tons of big stem plants and Java ferns, in a really a mature tank then you're probably going to need something that's heavy on both micro and macro nutrients.

If you have a tank that's full of all of those same dense plants I was talking about a really big jungle but you have a bunch of large fish like South American cichlids then you don't want to be adding a ton of macronutrients in there.

Besides the fact that you might run the risk of getting an algae bloom, discus and other species can be really sensitive to excess nutrients so in that case I would just get a separate micro and macro bottle and dose them separately.

I'd use that method I described earlier where you're testing your nitrates and then going off of that aiming to keep your nitrates below whatever level is appropriate for your fish.

As soon as nitrates drop under a certain amount (~10 PPM) you want to add some more macros in there and the only way you're going to be able to figure that out is to test it yourself. It's kind of a hassle in the beginning, to test your water quality fairly often but once you get an idea of how much your plants consume then you can kind of put it on autopilot and just go with the flow.

My favorite brands and products

What are some of my favorite brands and products? I'll go over three or four of my favorite brands… what I like about them what I don't like about them. There's far more companies out there and I'm not saying that these are the only good products out there to use these are just the ones that I have experience

with. I can tell you based off my firsthand experience that they're trustworthy

brands that will yield good results.

Look at the Super Helpful Table below to get an idea of what I’m talking about through this section. It lists all the fertilizers and percentages of nutrients. This layout is helpful to compare different products.

NilocG is a terrific brand. It's maybe one of the more affordable liquid fertilizers. NilocG's Thrive Plus is an all-in-one complete fertilizer that's intended for low PH systems. You definitely don't want to use this if you have a basic tank (high pH) because this will result in a lot of ammonia being produced.

NilocG’s Thrive for high pH systems or basic tanks is almost the same. Just use it for tanks with pH above 7. Both these fertilizers are packed with tons of nutrients, especially macros. They’re great to use for lush tanks with tons stems and mature java ferns.

If you look at NilocG’s Complete Low Tech Fertilizer it's basically the same thing except the nitrogen 1.24% instead of 2.56% so about half and you could look across at anything and really see that it's about half the nutrient content. So basically half of this is water or or basically twice twice as much water in this as these other ones.

2hour Aquarist is one of my favorite brands. I absolutely love this brand! APT1 also labeled APT0, kind of confusing is basically just micronutrients. You can use the table to compare it to APT3; it's the complete formula and it's got all the nutrients in there including micros and macros.

A good way to think about this is how it compares to another brand or product. The APT3 is lighter in macros compared to micros when you stack it side by side with NilocG’s Thrive. That’s a good thing to look for if you want to do a leaner dosing that pulls out more reds from your plants.

A couple last things I wanted to go over… The prices along the bottom are just rough prices and it's the start of 2024 so naturally things will change over time but this gives you a good idea of comparison.

If you like let's start with Leaf Zone, that’s going to be one of the most commonly available fertilizers found your nearest unnamed big box store. It's only got a couple elements in there and it's also super cheap, but that's why it's cheap.

Seachem Flourish is also fairly cheap and readily available but it's got all of the elements in there. It's even got calcium, which a lot of the other brands don't have. One thing I noticed because it applies to me since I use 2hour Aquarist and NilocG mainly and neither of them have calcium except for Thrive Plus.

That brings up an interesting conversation point that calcium is really important for your plants. It's an element that they absolutely need but it's also present in a lot of tap water especially if you have harder tap water. Where this could be an issue is if you have soft tap water like where I live. That’s likely if you live close to mountains. Water usually tends to be softer when you're closer to the source of water since it has less time to pick up minerals.

The hardness just reflects the calcium and magnesium present, so if you have soft water and you're using a fertilizer that doesn't have calcium or magnesium then it's important to you either add that to your water with some GH powder or you can use limestone. If you're using seiryu stone for your scape then it's probably already covered.