Have you ever tried growing plants in regular gravel?
And by regular gravel I mean the colored rocks sold in most pet stores.
Truthfully, most gravels are less than ideal for growing aquatic plants.
Plants like Java Fern and Java Moss will grow in tanks with regular gravel, but if you want to take you planted tank to the next level, consider buying a gravel specifically for growing plants.
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My Top Substrates For Planted Tanks:
For a detailed review of why these substrates are my go-to substrates for planted tanks, read my review below.
Why Aquarium Substrates Matter
Aquarium substrate is like potting soil for terrestrial plants, it provides a source of nutrients and allows plant roots to anchor themselves into something solid.
The benefits of aquarium substrate include:
1) Visual Appeal
While bare bottomed tanks have their uses, like raising betta fish fry or axolotls, aquariums with substrate bottoms look more natural (unless you use pink gravel…).
The right substrate can transform your tank from tacky to inspiring; instead of pink gravel, use natural substrate to mimic the colors textures found in the habitats of tropical fish .
The color of aquarium substrate plays a large role in visual appeal.
White aquarium substrate is not often found in freshwater settings, but may invoke the environment that certain cichlids live in.
Black aquarium substrate is especially good at making the color of your fish pop.
In fact, I find that cherry shrimp and betta fish look especially vibrant when placed in a tank with black substrate.
2) Nutrient Source for Aquatic Plants
If you plan to grow live plants in your tank, choosing the best planted tank substrate for your root feeding plants is often the difference between stunted plants and thriving plants.
In aquascaping, which is almost entirely focused on creating visual appeal with plants, selecting a substrate with the proper nutrients becomes crucial.
This is because plants take weeks if not months to grow in and need a constant source of nutrients (especially carpeting plants).
While these macro and micronutrients can be supplied by dosing liquid fertilizer, putting nutrient rich substrate in your planted tank provides a long lasting and easy way to grow aquarium plants.
3) Altering Water Chemistry
Some substrates promote “hard” water or water with a pH higher than 7 while other substrates release acidic compounds that bring the pH below 7.
Depending on which kinds of plants you are trying to grow and which types of fish you are keeping, one is likely preferable to the other.
If your tap water is not suitable for the type of fish you are keeping or the plants you are trying to grow, using distilled water and re-mineralizing it with the help of the right substrate may allow you achieve the appropriate water parameters.
4) A Surface for Nitrifying Bacteria to Colonize
Some planted tank substrates not only provide nutrients for your plants but also help nitrifying bacteria colonies.
You want nitrifying bacteria in your tanks because that is how tanks are “cycled.”
I explain below why one of my favorite substrates is ideal for both cycling tanks and growing plants.
Planted Aquarium Substrate Layers
Layering your aquarium’s substrate is especially useful for planted tanks and aquascaping.
In my own planted tanks, I typically add a first layer of red fluorite or laterite, mainly for iron, and then cover that with a layer of Eco Complete (reviewed below).
Finally, I add a layer of Fluval Stratum (also reviewed below), which does not compact and provides additional nutrients for plants.
How Deep Should Substrate for Planted Tanks Be?
The answer depends on which kinds of aquarium plants you are hoping to grow in the substrate and the size of your tank.
For my nano tanks—between 3 gallons and 7 gallons—I add three layers of substrate, which creates about 1-2 inches of substrate.
For larger tanks that may be impractical, but I find that the increased substrate depth in smaller planted tanks provides more room for plant roots to travel and creates more surface area for nitrifying bacteria to colonize.
Overall, I would lean toward a deep layer of substrate for planted tanks.
As a rule of thumb, for a 2 inch deep substrate bed, you will need about 1 pound of planted tank substrate per gallon.
List of Best Substrates for Planted Aquariums:
1) Eco Complete
Eco Complete is one of the most popular planted tank substrates on the market, and for good reason—its grows plants and it looks great.
Granules of this substrate vary in size, ranging from particles the size of sand to particles the size of peas.
Eco Complete is a volcanic substrate and is very porous, which provides lots of little spaces for beneficial bacteria to colonize.
Eco Complete actually come “pre-cycled,” meaning beneficial nitrifying bacteria are included in the bag.
You can tell that Eco Complete is pre-cycled because the substrate arrives wet, with a decent amount of liquid in it.
If you want Eco Complete’s cycling benefits, do not dump out this liquid. Instead, add some of it to the tank you are building.
While Eco Complete is not a substitute full cycling, it offers a boost to cycling and is a nice bonus.
A note of caution: make sure you look at the expiration date on the Eco Complete bag because the beneficial bacteria in the bag can die and may spike your ammonia if added to a newly cycled tank.
Performing extra water changes after adding Eco Complete to your tank will help prevent a surprise disaster.
Eco Complete is best for:
• Aquarists who want a proven substrate for growing plants;
• Those who want a natural black substrate;
• Those interested in aquascaping and planted tanks;
• Those looking for pre-cycled substrate.
Eco Complete Applications
Eco Complete is an excellent middle layer substrate for planted tanks and aquascapes.
The texture and consistency of Eco Complete is between sand and gravel—this volcanic substrate is essentially lava rock broken up into tiny pieces that vary in size.
This gives the substrate a natural, rugged look and the finer particles in the mix help hold plants firmly, preventing plants from floating up to the surface.
Fluval Stratum is also a volcanic substrate but the particles of this substrate have been formed into small pea shaped spheres.
The granules or pellets are mostly uniform in size, giving a unique appearance that reminds me of tiny black marbles (could just be me).
Fluval Stratum is excellent for freshwater shrimp tanks because algae and other tasty bits tend to grow on this substrate.
Cherry shrimp will spend their day picking off these algae and seem to prefer it to other substrates.
Fluval Stratum also provides a rich nutrient source for plants.
Fluval Stratum is best for:
• Planted Shrimp Tanks;
• Planted Betta Tanks;
• Those looking for a loose plant substrate.
Fluval Stratum Applications
Fluval Stratum is rich in nutrients, being a volcanic substrate, and makes an excellent top layer substrate.
Generally, I will use Laterite or Flourite as a first layer, directly on the bottom of the tank, and then cover that with Eco Complete, and then cover the Eco Complete with Fluval Stratum.
This provides three layers of nutrient rich substrate for plants to feed off on and showcases the visual appeal of the Fluval Stratum.
3) Nature Soil (Alternative to Fluval Stratum)
One alternative to Fluval Stratum is Nature Soil.
The particle size is similar but Nature Soil’s color seems to be slightly darker black.
Nature Soil pellets also seem “softer” than Fluval Stratum pellets, which feels like kiln hard baked clay.
I have used Nature Soil in a 5 gallon planted betta tank and it works just as well as Fluval Stratum.
Nature Soil seems slightly more dusty, the particles seems to crumble more easily than Fluval Stratum.
Nature Soil does indeed feel more like a soil, but plants appear to thrive in it equally as well.
Flourite is a kind of porous clay manufactured by Seachem and provides a rich source of iron, which is a vital nutrient for plants and one that is tricky to find in a form that plants can absorb.
Flourite is best for:
• Planted tanks and aquascapes;
• Iron hungry plants (like Amazon Swords);
• Layering substrates.
While Flourite works great as a base layer underneath a finer substrate, it can also be used as a substrate by itself.
Flourite particles, especially Flourite Red, look like pieces of flat rock, giving a very natural look.
I use Flourite in most of my tanks to ensure my plants have a decent source of iron as well as other micronutrients.
From personal experience, Seachem Red Flourite will turn your tank into red, muddy looking water, and it does not clear easily.
The solution is to pour the Red Flourite you plan to use into a bucket and hose it down with some force.
Once the water is swirling around you will need to pour out the water by tipping the bucket at a 45 degree angle.
The trick is to pour out the red cloudy water without pouring out the actual gravel.
It took me about 20 minutes of rinsing this way to clean about 2 pounds of fluorite for use in a planted tank.
While this method is tedious, it helps prevent your tank from being plagued by a cloud of red dust.
5) Laterite Based Substrates
Laterite is an iron rich clay-like soil that is porous and is typically sold in a fine powder.
Laterite can be used as a substrate on its own but make sure the granules are fairly large, otherwise you will end up with a cloudy tank.
Laterite functions best as a base layer in planted tanks with thicker gravel particles covering it.
Like red fluorite, laterite is an excellent source of iron and other micronutrients but needs to be rinsed repeatedly to prevent your tank from becoming a red, cloudy mess.
Laterite is best for:
• Planted tanks with heavy root feeders;
• Aquarists looking for a nutrient rich base layer.
Laterite is great for tanks that want to grow Amazon Sword plants, stem plants, and other hungry root feeding plants.
Laterite is an easy source of iron and works well as a base layer substrate in aquascapes.
Best Substrate for Betta Tank
When looking for the best substrate for betta tanks, deciding if you want a planted betta tank is important.
If having a planted betta tank is a goal, or if you want to leave the option open, Eco Complete by itself or covered with a top layer of Fluval Stratum makes an excellent substrate not only for your betta but for growing plants.
If plants are not important to you, the best substrate for a betta is one that you can easily clean, so that ammonia spikes do not kill your fish.
Sand is relatively easy to vacuum, and is my pick for best substrate if plants are not a priority for you.
Flourite Black Sand will make your betta’s colors more vibrant (unless you betta is a dark blue or black).
Even in a betta tank without substrate or with inert substrate like sand, plants like Java Moss and Java Fern will still thrive.
If you want to learn more about easy plants for betta tanks, check out my article here.
Best Low Tech Planted Tank Substrate
For low tech planted tanks, meaning tanks with no CO2 and no fertilizer, and conventional aquarium lights like a kit light, the best substrate is one that provides enough nutrients for undemanding plants like Crytocorynes and some stem plants.
You could try a sand substrate, but layering two or three substrates is likely to give your plants the best mix of nutrients.
If you are determined to grow plants like an Amazon Swords in your low tech setup, starting with a layer of laterite or Flourite Red and covering that with Eco Complete and/or Fluval Stratum is an effective way to supply your plant needed iron and other micronutrients.
My overall pick for a low tech planted tank substrate is Eco Complete.
Adding a layer Fluval Stratum or Nature Soil as a top layer would also provide additional nutrients and visual appeal.
Is Sand A Good Substrate for Aquariums?
Using sand for planted tank substrate is tricky and typically ends in dead plants and a tank full of algae.
The issue with small granule sand is that it compacts.
This means that gravity and water pressure are forcing the sand particles to pack themselves tightly against one another, preventing oxygen from traveling down into the sand substrate.
Over time, anaerobic bacteria (bacteria that do not need oxygen) colonize under the sand and begin releasing smelly gases.
While these bacteria may be able to help you cycle a tank, most people want to avoid rotten smelling bubbles rising from the substrate.
If you are interested in using sand as an aquarium substrate, spread it in a thin layer and avoid plants that have roots.
Plant roots need oxygen to grow and sand typically prevents a plant from getting the appropriate amount of oxygen and nutrients to thrive.
So, for a beginner, or someone who wants to focus on planted tanks, sand should generally be avoided.
Planted Tank Sand Substrate
BUT, if you are determined to use sand as a planted tank substrate, then I recommend Seachem’s Flourite Black Sand because its sand granules are larger than play sand and plants appear to do well in it.
The same company that sell Flourite Red and Black also sells Flourite Sand, which is dark black sand that seems to allow for better oxygen circulation to plant roots than other sand substrates.
But, your experience may be different, for better or for worse, when trying to grow plants in Flourite Sand.
Some people have success and appreciate how debris and fish feces collect on the top of the sand and then are swept into the filter instead of collecting underneath a gravel substrate where messy vacuuming is required.
But, that also means less debris is reaching plants roots and less oxygen as well, which can be detrimental to some plants.
If you are curious and want sand for a substrate, this is the kind to try but I would not call it an ideal planted tank substrate.
White Substrate for Planted Tanks
Black planted tank substrate is much more common but white planted tank substrate does exist.
Eco Complete’s African Cichlid substrate is a mostly white substrate that works well in planted tanks.
Eco Complete African Cichlid looks like crushed shells and rocks, mimicking the natural environment that shell dwelling cichlids and others call home.
The particles are smaller than gravel but larger than sand and look very natural.
Planted Tank Substrates to Avoid
Substrates that lack nutrients are not “bad” substrates but they will not help you grow aquatic plants.
If you are serious about getting your aquarium plants to thrive, you may want to avoid the following substrates:
1) Colored or Dyed Gravel
Besides looking unnatural (which is not always bad), low quality colored gravel seems to lose its color overtime, which means the dye leached into your water.
I avoid colored gravel for this reason as well as the fact that it provides no nutrients to plants.
Growing plants in sand is not impossible, but it can be tricky so, unless you want to experiment with something like Flourite Black Sand, I would avoid most sands if your goal is a vibrant planted aquarium.
3) Glass Beads and Marbles
There’s nothing wrong with marbles and glass beads as aquarium substrate, but growing plants is going to be a problem.
I bet you could get Java Moss to cover the glass substrate, but most aquarists should stick with a nutrient rich substrate optimized for plant growth.
4) River Stones
River stones will not hurt your plants, but they also likely inert, meaning they do not provide any nutrients to plant roots.
If you love the look of river stones, consider using plants like Java Fern and Anubias which do not require nutrient rich substrate.
Growing Plants Without Substrate
If you want to grow plants without nutrient rich substrate or if you want a sand substrate aquarium above all else, try growing plants that do not feed from their roots.
Plants like Anubias and Java Fern will gladly grow on a rock or chunk of drift wood, allowing you to have a planted tank without planted tank substrate.
Betta tanks are often kept without substrate but that should not prevent you from growing plants for your betta fish.
Check out my article on true aquatic plants that grow in low light, low tech setups here.
The substrates that I mention in this article are certainly not the only substrates that will grow plants but they are the substrates that have worked best for me.
If you are curious about a substrate not mentioned in this article, I encourage you to experiment with it and let me know how it goes.
Stay zen aquarists.