When you want to grow a beautiful, lush, planted aquarium, there’s one thing that you need to consider above everything else: Substrate!
Substrate is the “base layer” of your aquarium.
It provides a structural foundation for your plants to get their roots into, as well as supplying the essential nutrition and minerals your plants need in order to grow.
Common substrates include sand, gravel, clay, peat, soil or dirt, or a combination of two or more different kinds of material.
The challenge is choosing the right one for your needs.
How do you know which substrate is right for your planted tank?
In this article, we’ll look at how substrate supports your planted aquarium, and we’ll review six products that can help you choose the right kind of substrate for your planted tank.
Best Substrate Picks Compared
Last update on 2023-03-20 / Affiliate links / Images from Amazon Product Advertising API
What is substrate?
Substrate is the very bottom layer of your aquarium. It can be soil, clay, pebbles, gravel, or a combination of materials.
Think of substrate as the absolute foundation of your aquarium, because a lot depends on it.
Sand is one of the most common substrate types as it’s cheap, easily available and works for a wide variety of aquarium habitats. Lots of fish like to dig around in sand and hunt for food in it. We have a detailed article on aquarium sand.
Gravel is another popular option that works well because it’s very similar to the natural environment of many fish and plants in the real world. Gravel can be a good option as it will help root development in aquatic plants.
Coral sand is a good choice for aquariums with marine or coral fish. It’s bigger than sand, but smaller than gravel. It breaks down as it gets older, so watch for rising pH levels in your tank.
Soil is an excellent option for a tank that you want to plant out. It’s natural, most products are either packed full of organic micro-nutrients or have supplements added, and it will pack down tightly under the weight of the water to provide a good foundation for your aquatic plants.
What does substrate do?
Aquatic plants are just like plants that grow in the ground – they need the right kind of minerals and trace elements to grow.
This includes iron, nitrogen and magnesium.
Choosing the right kind of enriched substrate for your plants is a key part of keeping them healthy, strongly coloured, and flourishing in your tank.
Another great benefit of substrates is they have a lot of nutrients and this can help to stop your aquarium being taken over by algae.
The plants will grow quickly and absorb nitrates from the water – all of which helps to keep the water clean, sparkling and free from gluggy algae.
The bacteria in your substrate can help keep unwanted micro-organisms, toxins and other dirt and impurities at bay inside your tank.
Additionally, when your fish excrete waste matter, substrate can help to settle that matter at the bottom of the tank so that it isn’t floating freely inside the water – and this slows down the process of decomposition, which helps to keep your water clean.
How do you choose the best substrate for your planted tank?
It’s important to gather some knowledge about substrate before you put your planted aquarium together.
Don’t expect that you can just put in any old base layer and have it work.
You could waste a lot of time and money on expensive mistakes that could even hurt the fish in your tank.
Instead, make sure you know everything you can about these two questions before you go ahead:
What kind of fish are you going to keep?
What kind of plants do you want to grow?
Answering these questions will help to determine the right kind of substrate for your aquarium
Substrate also comes in lots of different types, colours and materials, and what you choose can dramatically change and enhance the look of your planted tank.
So there’s a lot to think about when you’re deciding on the best substrate for your planted tank.
Do your research beforehand and you can make sure you make the right choice.
Here’s a great video you can watch to learn more about how to pick the right substrate for your planted tank.
Know your fish
It’s important that you consider the kind of fish you’re going to keep, above all else – even before you start to think about plants.
Different fish also need different kinds of plants.
Some want plants they can hide in, or under – either because they’re shy, or because they like the shade.
Others want plants that they can nibble on.
There are other critical considerations too when it comes to pick the right plant for your fish.
For example, what kind of pH range do your fish like?
Do they need to be able to burrow into the substrate, create piles and slopes, or sift it with their mouths?
Are they tough critters that can handle gravel, or do they have delicate fins or barbels that need something softer?
Different kinds of fish require different kinds of substrate – for example, a pebbly substrate isn’t good for goldfish, as they might swallow the pebbles and hurt themselves as they’re sifting the substrate for food.
Equally, delicate fish like bettas might catch their delicate fins and tails on a gravel substrate that has sharp edges.
Once you know your fish, you can choose the right substrate and plant species to suit their needs.
Know your plants
So now you’re clear on the fish you want, and it’s time to consider the best plants for their environment.
Some plants need a firm substrate to root in so that they’re securely anchored to the bottom of the tank – while others can handle being rooted in a lighter or finer substrate.
Some plants will want a substrate that is highly nutritious and filled with minerals, so that they can feed from it and grow properly.
Different plants will need different feeding requirements.
And some, like water column feeders, don’t root and won’t care what kind of substrate you’ve got at all!
How much substrate should you use?
There are different schools of thought here – some aquarists like a light layer while others prefer a deeper one.
Plants that need a deep, dense structure will obviously need a deeper layer of substrate than plants that are light and tuck in easily.
A good rule to remember is that you will, in any circumstance, need at least 1 inch of coverage. You can go deeper to 2 or 2.5 inches, but more than that is probably overkill.
Bear in mind that if you want a 1-inch layer of substrate at the bottom of your aquarium, you’ll need to use 1 pound for every gallon of water in the tank.
6 substrates for your planted aquarium
1. CaribSea Eco-Complete Planted Black Aquarium Substrate
This darkly-coloured substrate is a popular choice among aquarists who are looking for a solid all-in-one nutritional performer as well as an attractive base layer for their tank.
Eco-Complete uses volcanic soil, which is naturally rich in minerals and trace elements, in order to deliver strong, lush growth for your plants.
Eco-Complete is advertised as containing iron, calcium, magnesium, potassium, sulfur and over 25 other elements, making it a biologically complete substrate that helps aid root development as well as helping to keep algae growth under control.
Because Eco-Complete is a volcanic soil, it’s a little different to your average gravel additive.
It has small grains that are finer than other gravels, which makes it suitable for bottom swimmers and invertebrates that like to hang out around the base of the tank.
These fine, porous grains contain live Heterotrophic bacteria that rapidly convert the waste matter from your fish into food that can support your plants.
This additional bacteria helps to shorten cycling time for a new aquarium and builds up strong colonies of micro-organisms in established tanks.
It comes ready to use, in a bag that has water added.
There’s no need to rinse, so you can put it straight into your aquarium, though be aware that it may leave your tank cloudy for a few hours.
Note that this is for new tanks only – don’t add this substrate to an existing tank with fish, as the ammonium spike can be harmful to them.
No paint, chemical coatings or dyes are used in this substrate, but because of its high mineral content it does have a slightly alkaline pH – so make sure you check that the pH level is suitable for the fish you’re keeping first.
One 20-pound bag of this Eco-Complete substrate will cover a 20-gallon tank floor with ease.
2. Seachem Flourite Black
We reviewed this excellent option for planted tanks as part of our article on choosing the right sand for your aquarium – you can check out the review here.
Flourite Black is a premium substrate that’s rich in nutrients.
It’s a porous clay sand rather than a traditional sea-type sand, and it’s specifically designed to support aquatic plants in your aquarium.
As it’s clay, this substrate has a higher iron count than some other substrate options, which means it can be a good choice for red plants, as they suck up iron to produce their bold colours.
It’s a great-looking sand with a dramatic black colour. It has very small grains that are especially fine – and the upside to this is that your aquatic plants will root quickly into this substrate.
However, the downside of the fineness is that it will need thorough and extensive cleaning before you can add it to your tank.
If you don’t clean it sufficiently, the tiny particles of the sand will stay suspended in the tank water for a long time.
Your tank won’t just be cloudy, but you’ll run the risk of damaging your water filter as well – so clean it properly. When you think you’re done cleaning it, clean it again!
Once it’s in your aquarium, you might also see some cloudiness from time to time as your fish, snails or other bottom-dwellers disturb the surface of the sand while they go about their daily business.
Don’t fret about this, it will settle.
Flourite Black is advertised to be free of any chemical coatings or treatments, so you can add it to your aquarium without needing to worry about a change in your pH level.
Another positive note is that you can also choose other colours if black isn’t for you.
3. Activ Flora Floracor
This substrate is described as a bio-active, nutrient-enriched gravel that has been developed specially for planted aquariums.
Activ-Flora is naturally rich in trace elements that your plants will appreciate - good nutrition is important for optimum health and growth, and without it, your plants will never achieve the lush, exuberant look that shows them at their best.
It also has heterotrophic bacteria to help keep your tank clean.
Activ-Flora comes in a range of rich and beautiful colours, so it is a popular choice with aquarists who are after a different kind of look for their aquarium.
For example, the red colour contrasts strongly with vibrant green plant growth and it can provide a real wow factor to an otherwise standard tank.
The grains of the gravel in this product are sized between 3.1 – 6.3mm, so it’s a larger particle size than some other options on the market.
It may cause some cloudiness at first when you add it to your tank, so be sure to give it time to settle properly.
This product comes in a 16-pound bag and it’s pH neutral.
4. UP Aqua Sand for Aquatic Plants
UP Aqua Sand is a light, grainy substrate that is nutrient rich and will help your plants root very easily.
It’s designed for tanks with plants, fish and shrimp.
The grains are dark grey to black in colour.
They’re consistent and uniformly structured, so they move very easily, like marbles flowing over one another, even though they’re different sizes. You can find grains from around 4mm to just under 2mm.
It doesn’t break down as it’s not a naturally organic material.
There’s very little dust involved with this product, and it says on the pack that you don’t need to rinse it before adding it to your tank.
You might be delighted to find that your aquarium is completely clear, right after you’ve filled it up.
But don’t be dismayed if you do experience some light clouding – this will clear in a few hours.
Then you can sit back and enjoy the modern, contemporary look that this substrate offers.
UP Aqua Sand comes in an 11 pound bag and it’s pH neutral.
5. Fluval Plant and Shrimp Stratum
Fluval Plant and Shrimp substrate prides itself on being specifically engineered for shrimp and plants.
This substrate is made from volcanic soil, which means it’s natural and rich in minerals.
It’s also light and porous and packed full of “plant micro nutrients” that will help stimulate growth in your plants.
It has a non-compacting structure that positively supports bacterial growth, which will help to keep your tank water clean.
The big selling point that Fluval emphasise is that the lightness of the substrate provides an excellent hiding place for shrimp fry to shelter until they’re big enough to enter the aquarium community safely.
This substrate will break down after 12-18 months so be prepared to replace it during that time.
And be aware that disturbing it while its in the tank is not a good idea – the pellets crush easily, and it can create a very untidy scenario in your water.
Fluval Plant and Shrimp Stratum comes in a 4.4 pound bag.
It’s good for a neutral to slightly acidic pH, which makes it a good choice if you’re keeping tropical fish and shrimp (obviously) along with most plants.
6. ADA Aquasoil Amazonia
The marketing gurus at ADA are earning their keep, because simply using the word Amazonia in the title of this product literally brings to mind images of lush, green, rainforest growth. Clever!
But this soil is more than just a great name.
It’s made of completely natural material that is processed into the fine granules that make up the product.
These granules are well-sized for rooting systems and will help your plants take shape quickly.
ADA Aquasoil Amazonia is rich in nutrients and helps to lower the pH levels of the water in your tank while softening it at the same time.
This is both a good thing and a bad thing – great for plants but it can be risky for fish, so you’ll need to keep an eye on your levels.
This soil is a good option if you are running a range of different plants in your aquarium as it will support many different kinds of plant life.
So that’s the down and dirty on substrate and how different choices can affect the plants you can grow successfully, as well as pair with the fish and other creatures you’ve stocked in your tank.
In our view, the best pick of the round-up is the CaribSea Eco-Complete Planted Black Aquarium Substrate.
This product gets rave reviews from aquarists all over the world, as the all-in-one appeal of a good looking base layer that also feeds a range of different plants is hard to beat.
It’ll keep algae to a minimum and make sure your plants have their best chance to grow lush, strong and vibrant.
Remember, when it comes to substrate, the best choice is the one that’s right for the kind of aquarium you’re running, the fish you’re keeping and the plants that work best in their environment.
We hope this article helped you with your research.
If you’ve got other good suggestions or points to make, tell us in the comments!