Best Substrate for Planted Aquariums

Written by Ricky

When building a planted tank, one of the hardest things to choose can be the substrate used in the tank. With so many options to choose from, it can be really tricky to know what substrates are gonna work best for your tank. What are the best substrates for planted aquariums?

For beginners, gravel is the easiest substrate to use for a planted tank with low-maintenance plants. More advanced aquarists will find that using a layer of fertilizing substrate, a plant-soil layer, and an inert substrate layer will provide the best results.

Keep in mind that there is so much more to substrates than simply using just gravel. Many plants have very specific needs as to their substrates.

Best Substrates For Low-Maintenance Plants

Low-maintenance plants are what we consider plants that can get their nutrition from the water column around them. Plants like this include:

  • Marimo Moss Balls
  • Amazon Swords
  • Anubias
  • and much more.

Plants that are low-maintenance are much more forgiving about the types of substrates you use. However, keep in mind that if you choose substrates specifically for low-maintenance plants, you shouldn’t combine them with high-maintenance plants unless you also use substrates for them, say in a pot or planter in the tank.

Luckily, most low-maintenance plants look pretty good. However, even for low-maintenance plants, for them to look their best they require as good of nutrition as they can get. Placing low-maintenance plants in a substrate mixture like that for higher-maintenance plants is not going to hurt your lower-maintenance plants, in fact typically quite the opposite will happen.

Best Substrates For High-Maintenance Plants

High-maintenance plants require a lot more from their substrates than low-maintenance plants do, as high-maintenance plants can’t obtain all the nutrition they need simply from the water column. However, often these more demanding plants pay off in spades with their elegant appearance.

Higher-maintenance plants include:

  • Cryptocoryne Balansae
  • Red Ludwigia
  • Tiger Lotus
  • Cryptocoryne Beckettii
  • and more.

A lot of these plants also have specific lighting, temperature, and flow speed requirements, so keep the plants and fish you are wanting to work with in mind as you choose the substrates and tank conditions.

Plants such as the Tiger Lotus really are fantastically stunning when given the proper conditions to thrive in. One of the key factors to their success is the substrate that you use. As GreenAqua mentions in the video above, it is best to use a fertilizing layer, a general plant-soil layer, and an inert substrate layer for your substrates.

Even if the gravel you buy has nutrients embedded in it, similar to Fluorite or other clay-based gravels, many of these plants require a pretty hardy and nutritious substrate to be able to truly thrive. We recommend the ADA Power Sand Advance as your initial fertilizing layer, followed by the ADA Amazonia version 2 plant soil.

After that, you can use a nice inert substrate as a more decorative layer, such as lava rock or other naturally colored substrates.

Planted aquariums can look wonderful with the right combination of plants, substrates, and fish.

Substrate for Planted Aquariums – What to Know

A substrate is what is put on the bottom of the tank, whether for plants to take root in or for fish to interact with. A substrate isn’t just used for nourishing plants, it is also used for aesthetic purposes.

While a substrate is not required for a tank without plants, tanks with plants need to have a suitable substrate for the plants in the tank.

Substrates can be anything from topsoil to lava rocks.

What kinds of substrates are there?

There are so many different kinds of substrates out there.

Substrates fall into a few categories:

  • Active substrates
  • Inert substrates
  • Complete substrates
  • Compound substrates

If that sounds complicated, don’t worry! It really is easier than it seems.

Active substrates are substrates that affect the pH balance in the water, typically through the shedding of nutrients and chemicals into the water. Examples of active substrates are:

  • Topsoil
  • Fertilizing layer
  • Aquasoil
  • Lava soil

Inert substrates do not affect the water’s pH balance. Inert substrates include:

  • Sand
  • Gravel
  • Lava rock
  • Petrified wood
  • River stones

Complete substrates can be used all by themselves if desired. Depending on what plants you are wanting to use, most inert substrates classify as complete substrates. Some active substrates are complete substrates, but others are fine enough to be considered as compound substrates.

Compound substrates require a layer of an inert substrate, also known as a cap, on top to prevent negatively affecting the water environment by clouding the water.

If you aren’t sure which of these substrates you want to use is, it will normally let you know on the bag.

Does the substrate I use really matter?

A lot of people tend to just chuck whatever substrate they can find for the cheapest price into their planted aquariums. Later on, they wonder why their plants and fish either didn’t thrive well or just straight-up died.

When it comes to the health of your tank and fish, substrates matter quite a lot.

Some plants require more nutrition than the water column can provide for them. These plants need a good combination of fertilizing soil and general plant soil, often with an inert substrate layer on top.

Other plants don’t need the same depth of nutrition as others and can acquire the nutrients they need straight from the water column itself. For plants like this, all they really need in a substrate is something to anchor themselves to. Inert substrates work great for low-maintenance plants for this very reason.

Generally, it really just depends on what the needs of your plants and fish are. Some fish need substrates they can interact with, like how Cichlids love to burrow around in the sand.

One thing is for certain, though: unless you are a trained professional, NEVER get your substrate from the wild!

Substrate obtained from the wild can very negatively affect a tank. Soils, sands, and gravels from the wild can carry all sorts of bacteria, algae, and other microorganisms that could have an adverse effect on your fish and plants.

Just like you wouldn’t go and eat a wild berry or plant straight off the bush just because it looked cool, you should not go putting things in your tank that you don’t know what they are or what’s on them. Aquariums are very delicate environments, and many fish and plant species are extremely sensitive.

Now, that’s not to say that you can’t put in your tank the awesome river stone or rock you found on your last camping trip, hike, or a trip to the beach. You will need to wash the rocks very thoroughly. Depending on the rock, it may even have to be washed around 20 times!

What Makes a Good Substrate?

Each substrate will have its own determining factors as to whether it is good or not.

Soils that nourish your plants well while not putting off a whole ton of ammonia or nitrogen are going to be the best options for active substrates.

For inert substrates, the qualifying traits depends on each substrate itself.

Gravel

Gravel is one of the best substrates overall, namely for its ease of use and general aesthetic appeal.

However, not all gravels are made equally. When selecting good gravel for your next planted tank, there are a few things to consider.

First, the thickness of your gravel matters; more than you might think. A great size for gravel is around five millimeters, with the gravel not exceeding 8 millimeters or being less than three millimeters. Any bigger than five millimeters and the gravel could potentially block root development and growth.

Gravel smaller than around three millimeters could damage roots or accidentally be ingested by fish that enjoy being at the bottom.

Secondly, make sure the gravel being used is not coated in epoxy. In quality epoxy-coated gravels, the epoxy may not wear off, but it definitely will wear off of many different gravels. More importantly, however, the epoxy-coated gravel is hard for plants to take hold of with their roots.

Sand

Sand can look absolutely fantastic in tanks. However, sand is also a huge pain to clean and is much higher-maintenance than gravel or stones.

With sand, the biggest thing is the color of the sand. Good sand is sand that looks good and won’t muddy up your water with leftover dust. Also make sure that the sand you use doesn’t leech silicates into your water, as some sands have been known to do that.

There are so many more different kinds of substrates than we can even list here. We highly recommend watching this video by the YouTube channel GreenAqua to learn more about substrates and what makes good substrates:

GreenAqua also has some wonderful videos on aquascaping for when you have your substrates picked out.

Hopefully, this article has helped you to learn more about which substrates are right for you and for your tank. Aquascaping may seem like a daunting hobby at first, but it is fairly easy to figure out and is well worth the effort.

If you like the article above, here are some other similar articles you should check out!

What’s the difference between emerged and submerged aquarium plants?

How many hours of light do aquarium plants need per day?

Can an aquarium have too many aquatic plants?

About the author

Ricky