The substrate you choose will have a significant impact on your freshwater tank. You must consider which type works the best for you since it is hard to change the substrate later. Different fish also respond differently to varying materials.
The 10 best substrates for freshwater aquarium include gravel, soil, sand, aragonite, vermiculate, and peat moss. Your choice will depend on the tank’s size and the fish you wish to keep. Coral, marbles, and clay are also great choices, but consider using layers of a few to keep your fish happy.
In this article, I will discuss the different aspects of substrates and what the ten best options are. When you finish reading, I’m sure you will feel confident picking a material that suits your tank.
Gravel is the best option for many freshwater tanks. The gravel can be made from tons of different materials and comes in just about every color there is. Plus, this material is easier to clean as uneaten food and fish waste can’t fall too far into the gravel, allowing you to vacuum it up with ease.
It also comes in different particle sizes, but many fish-lovers prefer the smaller pieces. That way, debris doesn’t work its way too deeply into your substrate.
When it comes to gravel, make sure it doesn’t have sharp edges as certain fish species spend a lot of time on its surface. This material is perfect for just about every species except catfish, which have soft skin instead of scales. They can be irritated by rigid substrates since they like to swim along the bottom of your tanks.
For a pop of color, try this 5lbs (2.27kg) bag of Spectrastone Shallow Creek aquarium gravel for under $15.
Using Gravel in Planted Tanks
Gravel is better than sand if you want to include natural plants as the particles are the perfect size for a plant to hold with its roots. You will also want to have a nutrient-rich layer under the gravel – aquarium soil is a good choice.
Pet store brands can make gravel from many different minerals. The most popular choice is pea gravel since it has a natural look and will not alter your tank’s pH levels. It also works exceptionally well for planted tanks. Pea gravel can be a bit sharp, so it is not suitable for fish that stick close to the bottom of your aquarium. Make sure you rinse it thoroughly before placing it in your tank.
Try this Maynooth 1/4″ Granite Mini Pea Gravel 5lbs (2.27kg) bag for under $15.
Pebbles are usually much larger than gravel and can be made from any material, including quartz, glass, plastic, and rock pebbles. Since this material is on the larger side, it can be more challenging to clean. You will want to maintain it so bacteria doesn’t build up and become toxic to your fish.
However, pebbles don’t impact the pH levels of your tank. If your water is already mostly perfect, then you probably don’t want to add something that will change it too much – making this a decent option. For anyone who has brightly colored fish, these Midwest Hearth Natural Decorative Polished Black Pebbles can make them stand out and cost less than $10.
If you have an aquarium vacuum, you can also safely use it on pebbles. This tool allows you to remove excess fish waste, food, and algae with ease.
Aquarium soil is nothing like the dirt you can find in your backyard. Brands formulate it to stay solid in water. Otherwise, it would become too murky to see your fish. This substrate is perfect if you want to grow a lot of plants. Many fish store formulas come with added plant nutrients.
Soil usually only comes in natural brown colors. These colors look lovely on their own, but you can spice up your tank by decorating with other, colorful substrates too.
Make sure you only use aquarium soil! Adding materials from your yard to your tank is dangerous for your fish. That includes dirt, rocks, sticks, and anything you don’t get from the pet store. They can harbor toxins and bacteria that can hurt your fish. Make sure you know what doesn’t belong in your fish tank.
Sand is another material that you can find in various grain sizes. You have coarse and fine options, along with plenty of colors to choose from. Sand is a natural substrate, so many fish species enjoy having it in their home. Sand also doesn’t trap uneaten food or waste, meaning it is easy to clean too.
If you enjoy decorating your tank, you will love sand. Many people enjoy using this material to develop unique aquarium styles since you can easily mix it with other substrates.
I like this Stoney River Black Aquatic Sand, which you can get for under $20.
Aragonite is a type of sand that consists of calcium carbonate. The calcium carbonate slowly releases into the water, which keeps pH levels up. If you need high pH levels, this substrate can increase them to around an eight or higher.
You can mix aragonite sand with other materials. However, due to how high it can raise pH, you usually find this in reef aquariums. Still, small amounts of aragonite can be used in freshwater tanks – if the fish species you have enjoy higher pH levels.
One bag of this AQUANATURAL Oolitic Aragonite costs under $20 and should last a while if you’re only adding a little at a time.
This type of substrate is a mixture of different minerals. Vermiculite is suitable for plants since it slowly releases potassium and magnesium, and it is best for tanks using multiple substrates. The best material to combine with it is gravel. Doing so gives your plants plenty of material to hold their roots; they also benefit from the nutrients vermiculate disperses into the water.
Plantation 8QT Professional Grade Vermiculite is a great option for under $15.
If your water is too hard and you want to soften it, you can add peat to naturally buffer the water. However, you will need to take some additional steps before you can use it.
First, check that the peat does not contain fertilizers or other chemicals. These substances can be toxic to your fish, so organic options are best. Next, place the peat in a plastic bag and allow it to soak for three days. This process balances out the pH in the peat.
You can spread the peat moss out as a substrate layer or even use it as a filter. To do this, you want to boil the moss in a nylon stocking, rinse it, then add it to your tank.
These Fluval Aquatic Peat Granules work well and cost just over $10.
Crushed corals are another material that keeps pH levels high and steady. This substrate is a popular alternative to aragonite since it keeps tanks at a level of about 7.6 easily. Coral is usually better for reef aquariums, but some species of freshwater fish thrive in it.
Mostly, freshwater African cichlids love this substrate. The crushed coral you find at pet stores will contain some aragonite in the bag as well. You can get several benefits from this, especially if you are keeping fish that enjoy hard water.
Marbles are best suited for breeding tanks – you will not want them in your everyday aquarium. They are challenging to clean due to how much space can be between them, and you will need to maintain and check on them often since they can easily trap fish waste and uneaten food.
However, these gaps are good for certain species’ eggs. They fall between the spaces in the marbles and stay there. Some fish will eat their eggs, so this ensures that your fry can safely remain hidden until they hatch.
Marbles do also make excellent decorative pieces. They are heavy enough to hold down fake plants and are suitable for fish species that like to dig up plants for fun. Before you add your marbles, make sure that you clean them thoroughly.
Finally, marbles work best for fish like bettas. They enjoy rearranging their tanks, and the smooth marbles will not irritate their thin fins. Many betta keepers will use both gravel and marbles in their aquariums.
For something extra fun, try these CYS EXCEL Flat Marble.
Clay is another excellent option for growing plants in your tank. It is ideal for water filtration and can handle ammonia well, and there are different types of clay that come with additional benefits.
A good option is a fluorite substrate, which contains a lot of iron. However, it does not offer plants much nutrition and can be harmful to some plant types. Some companies make clay pellets that resemble gravel, giving you the best features of both options.
However, clay can become mushy over time, making your tank dirty. Fluorite is one of the few clay types that can last for many years without compacting or disintegrating. For many fish keepers, this is the preferred option for using clay.
Overall, clay requires that you cycle your tank often. If you don’t mind spending more time cleaning your tank, it can be very worth using as a substrate.
For the best of both worlds, try these Elive AquaDuo Bio Growth Clay Pellet for less than $10.
Using Multiple Layers of Substrates
Another option is to build layers with your substrates, which is best if you want to have many plants in your tanks. Your bottom layer should contain peat moss or aquarium soil. These substrates are great for growing plants, as they hold their roots and provide nutrients.
Next, you want a more prominent grain of substrate. You can use gravel or pebbles, depending on the species of your fish. On top, you can place some decorations, as long as they are safe for your fish species. Treated driftwood, fake or real plants, and other store-bought decorations are always a fun addition.
Many dedicated fish keepers love using multiple layers of substrate in their tanks. It allows them to design the aquarium how they like and make a more natural environment for their fish.
Substrate additives are great for the bottom layer of a tank. Companies will usually mix them with soil or minerals, and they come in powder or capsule form to add bacteria or nutrients to the substrate.
They are helpful if you want to promote an environment that is good for healthy bacteria. Plus, you can use additives to give your aquarium plants essential nutrients. Additives offer plants these nutrients through their roots, which ensures they keep growing.
Some types of substrate additives can include activated carbon. This material helps to keep your tank crystal clear, allowing your fish to see easily. Carbon also helps manage contaminants, such as chlorine, in the water.
However, you should still always make sure your fish species are not going to be harmed by the substrate additives. They can change the pH levels of the water and other aquarium factors. Always look into the products you are adding to your tank- doing so can save you a lot of time and energy.
How To Choose the Best Substrates for Freshwater Aquariums?
The substrate is an essential factor in the nitrogen cycle. It gives good bacteria a place to grow, where they then manage toxins in the water. The substrate is also necessary for your live plants to take root and absorb nutrients.
The substrate is also an essential part of your design. Many people enjoy taking the time to select their substrate, set it up, and decorate their tanks. If you love making unique aquarium setups, you will likely spend a lot of time thinking about what materials to use.
Before you get a new substrate, you should consider the features of each type. They can have a different impact on your fish and come with certain benefits. You should be familiar with them so you know what works best in your particular tank.
Plenty of substrates come in a wide selection of colors and designs. You can choose from natural-looking particles to brightly colored stones. What you pick is up to you and the design you’re going for. You can find just about any color online or in a pet supply store.
Dark substrates make bright fish stand out, while a light material makes darker fish look more vibrant. You will also want to consider the color scheme of the room where you plan on keeping the tank.
Finally, the color can hide whether the substrate is dirty. Brown hides it well, while white does not. If you want to use white, you may end up changing it more often than you would like.
Effect on Fish
The substrate you choose will also affect your fish. You want to avoid glass since the pieces can have sharp edges. Very light substrates can also stress your fish when bright lights shine on them. Some substrates can provide nutrients to the tank – there is a lot to consider!
Fish with delicate, flowing fins tend to do better with larger particles. For instance, a betta fish might catch their fin on a sharp piece of gravel, and bottom-dwellers, like catfish, also need soft materials on the floor of the aquarium. They don’t have scales, and certain substrate materials can easily harm their thin barbels.
Before choosing a new substrate, do some research into your particular fish species at home. You want to create a habitat that they feel comfortable in and looks appealing to you.
Impact on PH Levels
Each species of fish requires a certain pH level in the water. For anyone who needs to raise the pH, you will want to use substrates such as crushed coral, petrified coral, shells, or even limestone. These materials can raise the pH more than expected, so I recommend you check the levels often.
However, some fish require lower levels in their habitat. If you want to lower the pH, you can add peat moss. This material filters water, which causes the pH to go down. Peat moss works as a substrate layer on its own, or you can add it as a decorative piece in one part of your tank.
Substrates come in plenty of different particle sizes. You can find large rocks made to imitate the ones you’d find in a river; sand, on the other hand, is made of very tiny grains. Each comes with its own pros and cons as well.
Large rocks are easier to clean but can trap uneaten fish food underneath. If left for too long, this can cause bacteria to build up. Small particles, like sand, can irritate fish that like to hold the substrate in their mouths. Sand is also much harder to clean.
Overall, you want to pick a type of substrate that works for your fish. Make sure you check out your species’ natural habitats online for some ideas. Some fish love small particles and use them to build their nests; others prefer to have large particles around.
Adding Substrate to Aquariums
Once you have your perfect aquarium substrate picked out, you will need to know how to add it to your tank safely. Rushing the process can cause fish harm if you are adding the material to an established tank.
When adding materials to a new tank, you need to rinse your substrate with hot water but don’t use any soap. You should also rinse any decorations you want to put in the tank. Then, slowly fill the bottom of the tank with your substrate and add your decorations.
Once that’s done, you can fill your tank with water. You want to do this slowly so as not to stir up your substrate. Finally, you can turn on your filter and heater. It is best to let your tank sit for a few weeks without adding any fish. That way, you can monitor it and know when it is safe to put them in their new home.
If you are adding new substrates to an established tank, you will need to be careful. Before you add anything, always remove the fish. You may also need to lower the water level in your tank, as adding new materials could cause it to overflow if it is too high.
Rinse and clean your substrate first, then use an empty water bottle or cup and add the materials into the tank. To do this, fill the water bottle with your substrate, then slowly allow the aquarium water to enter it. From there, you can pour the substrate where you want it.
Why You Shouldn’t Remove Old Substrate?
You will want to leave old substrate alone in established tanks. Beneficial bacteria grow there and are essential to the nitrate process. They remove toxins that would otherwise harm the fish in your tank.
When you completely remove your old substrate, you are also removing those good bacteria. After your new substrate is added, it can take a long time before they start removing toxins at the same rate. So, if that were to happen, your tank could see dangerous spikes in ammonia or nitrite levels, which would be extremely dangerous for your fish.
If you have an established tank, I recommend you leave your old substrates alone. You can still safely top it off with new materials or add some plant tabs to bring nutrients back into your soil layers. If you do have to change your old substrate, make sure you take your time and do so in a way that is safe for your fish.
When To Leave Your Tank Bare?
There are certain cases where you might leave the bottom of your tank bare. Some breeding tanks have no substrate, but it will depend on the type of fish, and many fish species prefer different materials during this process. You might also want to consider this Capetsma Acrylic Breeding Box.
Some people will also set up a hospital tank with less or no substrate so that they can keep an eye on the quarantined fish.
However, many species of fish feel more comfortable with a substrate. The flooring helps to circulate water and allows beneficial bacteria to grow. Plus, if you want plants, you need a substrate for their roots to spread out.
How To Clean Your Substrate?
You will need to occasionally clean your substrate since uneaten food and fish waste can build up there. There are a few ways that you can do this.
Clean New Substrate
Here is how you can clean new substrate that has never entered a tank:
- Open your substrate bag and add about ⅓ of it to a bucket.
- Place the bucket under your tap water and allow it to flow into the substrate.
- Stir the substrate with your hands.
- When the bucket is full, shut off your tap, and continue stirring the substrate.
- Remove the water.
- Repeat the process.
This process can take a long time. You will want to keep repeating it until the water remains completely clear after rinsing. When it is clear, you can then pour the substrate into the tank.
Clean Established Substrate
You must clean the substrate in your tank occasionally to keep the environment clean. You can use special gravel cleaner tools, such as the Hygger Aquarium Gravel Cleaner, which will suck up the waste that builds up at the bottom of your tank.
Many pet shops suggest that you clean your substrate once a month using an aquarium vacuum, and you will also want to clean the sides of your tank. Going through this process ensures that your fish live in a healthy and clean environment.
If you don’t have a vacuum, you can gently stir up the substrate to allow debris to escape. Your filtration system will then suck up the waste. Change the filter afterward, and make sure your fish are not in the tank when you do this, as it can cause them a lot of stress!
Use Aquarium Livestock
The final method for cleaning aquarium substrate is to use livestock or a “clean-up crew.” In fish keeping, this refers to any creatures that search the substrate for food. Shrimp, catfish, and snails are some of the most popular options for a freshwater tank.
Even goldfish love digging through the substrate for food. Keeping a few goldfish in a large tank can help out a lot as long as they are compatible with your other species. Goldfish do eat shrimp and snails, so make sure not to put them together.
Of course, you should still clean your tank often, even with plenty of clean-up crew members on board. They remove excess algae, dead plants, and other debris, which helps keep the tank clean. If you notice the substrate is gathering too much waste, you will still need to vacuum it.
Finally, make sure you remove dead snails right away. Their bodies can cause ammonia to spike in the tank, which can be very harmful to your fish.
There are many different kinds of freshwater substrates for you to check out! While gravel is the most popular option, you can also use other materials. Plenty of people enjoy decorating their tanks with a mixture of soil, peat, gravel, and pebbles, and there are many aquarium design examples online for inspiration.
As long as you are using safe substrates for your fish species, you can make your tank look however you want. Decorating the aquarium and choosing new substrates can be a lot of fun!
Let me know what your personal favorites are.