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Aquarium substrate is an essential part of any planted tank. It gives your plants somewhere to root and provides essential nutrition. But it’s more complicated than simply buying any old substrate and expecting to grow great plants. This may work sometimes but if it doesn’t you’ll be stuck wondering why.
There are some important things you need to understand about aquatic plants to ensure success. In this article, you will find reviews on some of the best substrates for planted aquariums. More importantly, you will find information on finding the best substrate for you.
Substrates reviewed in this article include:
- Carib Sea Eco Complete Planted Black Aquarium Substrate
- Seachem Flourite Red Clay Substrate
- Fluval Plant and Shrimp Stratum
- ADA Aqua Soil Amazonia
- Spectrastone Shallow Creek Premium Aquarium Gravel
What type of aquatic plants do you want?
Not all plants have the same nutritional requirements. Not all plants uptake those nutrients in the same way. Fortunately for us, there are two general categories.
Those that feed on nutrients in the water column and those that feed on nutrients in the substrate. While both types can get a little nutrition from the other source it is important to know the difference. There are also plants that fall in between these two categories and are equally suited to feeding on the water column as well as on the substrate.
If you can’t find a clear answer as to whether your plants are root or water column feeders don’t fret. Just make sure to have nutrients in both the substrate and water column and you’ll do fine.
|Aquarium Plant Types|
|Water Column Feeders||Root Feeders|
|Amazon Sword Plant|
Water Column Feeders
Water column feeders get the majority of their nutritional requirements directly from the water. Much of this nutrition comes from fish waste. Most water column feeders are either stem plants or floating plants.
Due to the way these plants take up nutrients they do not need a rich substrate. While the plants can soak up a little nutrition from the substrate most of it will be a waste. These types of plants really only use substrate as a place to anchor their roots.
Water feeders give you the option to use basic affordable substrates such as gravel or sand. These substrates don’t contain or hold any nutrients but a water column feeder will do fine in them.
On the other side of the spectrum are the root feeders. These plants take up nutrients the way most of us are familiar with; through the roots. Since they do most of their feeding through their roots they need a substrate rich in nutrients.
These rich substrates are normally clay or soil-based and have added amendments. These work great for root feeders but they are not essential. Many people have been successful using root tabs in gravel for instance. These root tabs may also be used to recharge a depleted substrate.
Keep in mind that these richer substrates have organic material that will essentially rot or break down in your aquarium. This will effect your water hardness and pH.
What should you use if you want to grow both types?
What if you want to grow water column feeders and root feeders in the same tank?
You could use a complete substrate for the whole tank. You may spend a bit more than you need to but all of your plants would thrive.
You could also mix a complete and an inert substrate. This could be done by mixing them together evenly. Or, you could spot treat and just use the rich substrate where you plan to put your root feeders.
Another more affordable alternative would be to use an inert substrate and amend it with root tabs.
Hard Water vs Softwater
Do you have hard or soft water? What’s its ph? These water parameters are important because they may affect what substrate or amendments you should use.
Hard water is water that has a pH of 8.5 or higher. It also has a lot of minerals such as calcium or magnesium. Soft Water on the other hand will have a pH of 6.5 or lower and few minerals present.
Why is this important? Because the type of substrate you choose may negatively affect your pH. Certain nutrients are locked up and not available to your plants at extreme pH levels. This can cause a nutrient deficiency in your plants. Not to mention this may kill any fish you have.
Fortunately, many substrates will state on the bag whether or not they alter pH. An active substrate will likely affect pH while an inert substrate will not. For instance, if you already have low pH water don’t add in a substrate that will lower pH further.
So please, get yourself a water test kit and test your water before adding substrate. Test kits are affordable and simple to use. If you need to adjust your pH there are buffer solutions to adjust it up or down.
What Are the Types of Aquarium Substrate?
Aquarium substrates come in a variety of colors, textures, and intended uses. The most common substrates used in aquariums are complete, clay, gravel, sand, and soil-based substrates.
Complete substrates are produced artificially. They are designed to provide all the necessary nutrients and minerals to your plants. A complete substrate will also likely be biologically complete. This helps to establish the nitrogen cycle in new tanks.
Minerals commonly found in complete substrates include iron, calcium, magnesium, potassium, and micronutrients. These components make a complete substrate an excellent for sustaining plant life.
Some complete substrates are also manufactured to inhibit aquatic algae growth. This added benefit can make maintenance of your tank easier (source 5).
Be aware, however. These are active substrates and can affect your water hardness and ph.
Clay substrate provides great support for roots and has an excellent cation exchange capacity. This means that it is great at storing and releasing nutrients. Clay is often mixed with other substrates to provide adequate nutrients.
Common types of clay such as Flourite contain trace amounts of iron and other micronutrients. These are essential for maintaining a healthy planted aquarium.
Sand is a thoroughly cleaned, natural and generally fine substrate. It is a fantastic choice for delicate fish species that like to burrow.
Sand is an inert substrate. This means that it contains no nutrients and will not affect water pH. So this a decent substrate for water column feeding plants as long as you have nutrients in your water.
You can also mix sand with other substrates, such as clay, to provide nutrients for root feeding plants.
The type of sand does make a difference.
The cheap play sand you get at any store isn’t well suited to a planted aquarium. It is too fine and will eventually get packed down. This will make it difficult for your plants to spread their roots through the substrate. To avoid this make sure you get an aquarium specific sand.
Gravel is a common substrate choice for freshwater aquariums. Gravel comes in a multitude of colors and sizes. Coloring can be achieved through a natural process or can be the result of a dying process.
When looking for gravel as a substrate, it’s important to note the dye. If a dye is composed of acrylic paint, it can be detrimental to your aquarium water chemistry. Ensure the dye is covered by a natural polymer seal.
Gravel can be very coarse and pea-sized, or it can be very fine (source 5). It is composed of any hard, lime-free mineral such as quartz.
While it is useful and can add aesthetic value, gravel should not be sharp. Sharp gravel can hurt fish who are bottom dwellers or fish that burrow (source 1).
Soil-based substrates are soft in texture and versatile. Soil substrates are often composed of peat, which is decomposed plant matter.
This substrate has a high cation exchange capacity. This is great for storing and releasing nutrients but also has a water softening effect.
If you have a burrowing fish, soil is a soft and safe place for them to create a home. An unfortunate aspect of soil-based substrates is the tendency to cloud the water. This can turn your water a yellow or brown color.
There are ways to mitigate this which includes sifting, rinsing and drying. For these reasons, soil-based substrates are best left to the more experienced.
Best Substrate For Planted Aquarium
Check out these reviews to find the best substrate for your aquarium plants!
Carib Sea Eco complete is made primarily from volcanic basalt. Using this parent material has a lot of benefits. It’s naturally very porous which creates a large surface area. This creates an ideal environment for beneficial bacteria that aid in nitrogen cycling.
This is a complete substrate so it contains all of the essential minerals and nutrients. It will work for root feeding plants as well as column feeders.
A unique feature of this substrate is that it comes “biologically complete”. This means that it comes pre-charged with beneficial bacteria responsible for nitrogen cycling. This should result in a shorter period of time to establish your new tank.
One potential disadvantage of this substrate is the fact that it may increase your pH and water hardness. Be careful when adding this to an established aquarium due to the potential change in water chemistry. Test your water before and after and be prepared to use an acid buffer solution.
- A complete substrate that contains all essential minerals and nutrients
- Comes “biologically complete” to jump-start the nitrogen cycle
- No rinsing necessary
- Volcanic material had great nutrient storage capacity
- Can raise water pH which may kill inhabitants
Fluorite is stable porous clay gravel that is a popular aquarium substrate. While Seachem offers Fluorite in black I prefer the red which gives the tank a little more color.
As a stand-alone substrate, this will grow most plants on its own. But if you have any heavy root feeders you will eventually need to add some nutrients. Root tabs are a great way to do this.
This also won’t alter your water pH which is a plus.
This clay substrate definitely needs to be rinsed prior to use. It has a lot of fines that will definitely cloud up your aquarium. Learn how to wash flourite here.
A great way to rinse the substrate is with paint strainer bags and lots of water. Best to do this outside with a garden hose if possible.
- More colorful than the black substrate
- Great nutrient storage capacity
- Grows most plants without additional fertilizer
- Won’t alter water pH
- Can cause cloudy water, needs lots of rinsing
For the experience shrimp keeper water quality and pH is a very real concern. There are lots of substrates out there that may harm or kill your shrimp.
For those of you out there that want to keep shrimp and plants, Fluval Plant and Shrimp Stratum is for you.
This substrate supports slightly neutral to acidic pH. This is ideal for most plants as well as those shrimp of yours.
Fluval Plant and Shrimp Stratum comes from Mount Aso Volcano in Japan. As with any volcanic substrate it has a naturally light porous structure.
This helps with nutrient holding capacity as well as providing lots of surface area for beneficial bacteria. You also won’t have to worry about it discoloring your water.
Unfortunately, it can also make anchoring the roots down more difficult. With rooting plants, you may need deeper substrate to keep them anchored.
- Slightly acidic to support shrimp
- Added micronutrients, will grow all plants
- Porous material great for nitrogen cycling bacteria
- Black color draws attention to inhabitants and plants, not the substrate
- Very light, can be difficult to anchor roots in
Most substrates for planted aquariums are made from clay or volcanic material. ADA Aqua Soil Amazonia, however, is made from actual soil.
This makes it rich in organic elements and nutrients. Because of this, it will grow any aquatic plant to include the most demanding root feeders.
This organic matter does cause some initial water cloudiness. When first added there is also a potential for ammonia spikes. This will go away in a week or more with proper maintenance and water changes.
Due to this, I recommend a fishless water cycle to prevent die-off of fish. For the beginner, ADA does make an Amazonia Light which presents fewer problems.
This substrate does have a tendency to soften the water and lower the pH of the aquarium. This can be a good thing if you are starting out with alkaline water that has a higher pH.
- Very rich organic substrate
- Demanding plants will thrive
- No fertilizer necessary
- Softens water and lowers pH
- Not beginner-friendly
- Causes initial water cloudiness and ammonia spikes
I don’t know about you but I really like the natural look of light-colored gravel. It has a bit more character than a lot of the dark substrates for planted aquariums. A great choice for gravel is Spectrastone shallow creek premium aquarium gravel.
The downside to gravel in a planted aquarium is that it doesn’t provide any nutrients for plants. I wouldn’t recommend gravel for demanding root feeders due to this.
But if you do want to use this gravel for root feeders added nutrients are a must. These can come in the form of liquid fertilizer or root tabs.
Keep in mind that with water column feeding plants you will still need nutrients. Your plants won’t have any nutrients if you place them in a new tank with only this gravel. Nutrients need to come from fish waste in an established tank or from liquid fertilizer.
Spectrastone uses a non-toxic plant-based coating on this gravel which is great. Being an inert substrate it also won’t affect your water pH.
- Great natural-looking aesthetics
- No rinsing required and no cloudiness
- Easy to clean and maintain
- Non-toxic plant-based coating
- Won’t alter water pH
- Contains no nutrients for your plants
- Not great for root feeders
So What’s the Best Substrate for Planted Aquariums?
The answer is it all depends! There is no one substrate that is the best for all people in all aquariums. There are a wide variety of factors that will determine what’s best for you.
All of my reviewed substrates will work great in the right situation. It all comes down to you knowing what you want to plant, what fish life you want to keep, and your starting water parameters.
If you still have questions or want to learn more, read on.
Planted Tank Substrate Mixes
There isn’t anything keeping you from using more than one type of substrate in your aquarium.
Capping a base layer of substrate with an attractive gravel or sand is a popular option. Many complete substrates are very dark and not particularly attractive. They can also be light and easily cloud up your aquarium.
Placing a gravel cap over this type of substrate not only gives a better look but aids in holding it down.
You may also want to mix in certain substrates to bring the pH of your water up or down.
Or, maybe you want to stretch the value of that premium substrate by mixing it with low-cost gravel.
There are lots of options here so don’t be afraid to experiment!
How Much Aquarium Substrate Do I Need?
This is a common question for people are ready to buy their substrate.
The short answer is enough to fill the bottom of your aquarium to about 2-3 inches. This is more than you would need for an aquarium without plants.
There are a couple of reasons for this. First, your plants need enough substrate depth to adequately root. With some volcanic based substrates, you may need more than 3 inches. This is because this substrate is very light and doesn’t hold roots down well.
Another reason is nutrient capacity. Your substrate has only a finite amount of nutrition available for your plants. The less substrate you use, the less total nutrition will be available.
This means with less substrate your plants will exhaust the nutrients in the substrate much faster. You will have to replace the substrate, amend it with root tabs, or fertilize it much sooner.
How much do you need to buy? A good rule of thumb for gravel is 1 pound gravel per one gallon of water. This doesn’t apply to other substrates however, as weight by volume can vary dramatically. For this reason, it’s best to check for product-specific recommendations.
When Should I add plants and fish?
This depends somewhat on the type of substrate you are using.
Generally, you should add the plants right away. They are not as sensitive as fish or shrimp when it comes to fluctuations in the water conditions. They will also aid in getting the nitrogen cycle started in your aquarium.
Fish or other aquarium inhabitants may need to be added after the tank has cycled. With nutritionally complete substrates there is often an initial ammonia spike in the water. This is fatal to most fish but will stabilize once the beneficial bacteria have become established.
Can I use topsoil?
Topsoil has been used successfully by many experienced aquarists. This is due to a few advantages it has over commercial planted tank substrates.
It is far less expensive than the fancy substrates sold specifically for planted aquariums. If you have a large aquarium using a premium substrate can cost you quite a bit of money. Topsoil, on the other hand, is much more affordable.
Topsoil is also far more nutrient-dense than most of these. This means that it will support plants for much longer without added fertilizer.
One of the problems with using topsoil is it can be very messy. Without a plan, it will cloud up your water with the slightest disturbance. A great way to counteract this is to add the topsoil and then cap it with aquarium gravel.
The biggest problem is that topsoil can have very unpredictable effects on your water conditions. Not all topsoil is created equal. You can have different effects with different topsoil. You may experience swings in ammonia, pH, and water hardness.
This can be mitigated through a process of mineralization. This involves screening the soil, rinsing it, and drying it.
This process is time-consuming and messy. For these reasons, the beginner should avoid using topsoil.
Final Thoughts On Substrate
If you made it this far you know how important substrate is for your planted aquarium. It can be as easy or as complicated as you want it to be.
Just don’t get so overwhelmed that you never get started. Grab an aquarium, some plants, a substrate and get going!