Once you got your new fish tank and stand set up, the next thing you should take into consideration when it comes to building your aquarium is the substrate. There are many types that provide different benefits to the water parameters, fish and plants.
This guide at Aquarium Blueprints will help you determine the best substrate for your tank.
Bare Bottom – The Cleanest “Substrate”
So what is the cleanest substrate in your aquarium? The answer is having nothing at the bottom at all. This is because fish poop and food can get trapped in the pebbles, sand and/or whatever substrate your are using. If left unclean, the ammonia, nitrite and nitrate could rise to unsafe levels (if your tank is fully cycled, you only have to worry about rising nitrates).
Another benefit to having a bare bottom tank is that it will be much easier to clean compared to tanks that have substrate cover the bottom. The wastes are easier to spot and you don’t need to be separate the fish poop and food from the rocks, pebbles and/or sand. Not to mention that your filter will have an easier time picking the detritus in your tank.
One downside is that your fish can become spook and/or disoriented in a bare bottom aquarium. This only applies to glass tanks that are placed on stands that only support the edges, which makes the bottom panel see-through. To make them more comfortable in this scenario, we recommend covering the entire bottom panel from the outside.
With bare bottom tanks, you may also run into a lack of beneficial bacteria that converts ammonia to nitrite and then nitrite to nitrate. This is because substrate provide a ton of surface area for the bacteria to grow. You can get around this potential issue by having a filter that contains materials that provide plenty of surface areas, live plants that feed off the water column and don’t need soil (i.e. Duckweed, Hornworth, Java Moss and Java Fern), in addition to keeping up with your water changes.
Before we begin look at the different types of fish tank substrates, let’s talk a little about how much you should add to your aquarium. Most fish keepers like to add enough to cover 1 to 2 inches at the bottom. If you want to grow plants that need soil, then a depth of at least 2 inches is recommended. Some notable plants that grow in the soil include Dwarf Hair Grass, Dwarf Sagittaria, Micro Sword and Water Sprite.
As we mentioned above, aerobic bacteria will grow on the substrate. Thus, the deeper the bed is, the more surface area your tank will have to keep you water free of ammonia and nitrite.
Aquarium substrate are usually sold per pound. A general guideline to follow is to buy 1 pound per gallon of your fish tank to get a depth of around 2 inches.
If you decided to have an deeper bed (at least 3 inches), then you will be able to grow anaerobic bacteria that will help remove nitrate from the aquarium as well. This bacteria type will convert nitrate to nitrogen gas. The gas will then work its way through the water column and dissipate at the top into the air.
One last factor to consider when it comes to substrate depth is that the pebbles, sand and/or whatever you decide to use will take up space. As a result, you will get less space for to add water as well as less room for your fish to swim around.
Decorative Pebbles And Gravel
There are fish tank substrate designed to be decorative. These pebbles and gravel provide surface areas for beneficial bacteria to grow and nothing more. With that said, you will be able to get artificial colors on the bottom of your tank that you won’t find if you use natural substrate.
Best Substrate for Bottom Dwellers
If you are planning to keep Corydoras and/or Loaches, then we recommend getting a sand substrate. Both fish species love rummaging over the sand in search of food. Assassin’s Snails and Malaysian Trumpet Snail will also thrive using this particular substrate.
When picking a sand substrate, we prefer one that is has a smaller grain size. This is because food and fish waste are less likely to be trapped when compared to sand with bigger particles. With that said, smaller particles can become an issue as it is easy to kick up to the water column and end up being sucked into your filtration. So, you might want to be careful during water changes if you decide to use this type of substrate.
The substrate we used in our tank is the CaribSea Super Naturals Moonlight Sand Premium Aquarium Substrate (you can find our review for this product here).
If you are planning to grow plants, then you should look into getting fertile soil. As we mentioned above, Dwarf Hair Grass, Dwarf Sagittaria, Micro Sword and Water Sprite needed to be planted in a substrate that is nutrient rich.
Keep in mind that a planted soil substrate will gradually lose its nutrients over time. If you want to keep your plants healthy, you have to eventually use root tabs and/or water fertilizers.
Best Substrate for Raising and Lowering pH
If you want to raise the pH of your waters, then we recommend using crushed corals as a substrate. The corals will leach into the water, the rate of which depends on how acidic your water is. As a result, the pH will be raised and stabilized. The only issue is that the corals are sharp, which could damage the barbels of bottom-dwelling fish like Corydoras and Loaches.
If you want to keep these species while also wanting to raise and stabilize your pH at the same time, then we recommend using a sand substrate and then add in the crushed corals to the tank via fine meshed bags. Alternatively, you can put the crushed coral in your filter if you have room.
If you want to lower your pH, we recommend using soil made for shrimp. These are safe for fish and will keep your parameters at around 6.5 pH.
Keep in mind that the effects of crushed corals and pH lowering soil will decrease, and eventually go away after some time. Therefore, you will need replace the substrate.
If you want a clean looking aquarium, then you probably don’t need a substrate.
Sand substrate are best if you have bottom feeding fish or other aquatic pets that sift through the sand.
If you want to grow rooted plants, then you should get a fertile soil substrate. Last but not least, you should get crushed corals to raise pH and a shrimp substrate to lower pH.
In terms of depth, we recommend filling you tank up with at least two inches of substrate to give plenty of room for your beneficial bacteria to grow.