Posted 8th June - Kalem Holmes
Instagram: @ Kalemsfishtanks
Substrate is the one of the most important factors for success in a planted aquarium. It is how your plants will receive the majority of their nutrients needed to grow. A good substrate has the ability to hold in nutrients for your plants to use as needed. If a poor substrate is used nutrients will be free floating in the water. Your plants can still absorb these nutrients but it happens at a slower rate and gives algae a chance to use them as well. This being said good substrates can be filled with nutrients pushing the rest to the water column so these problems can still occur.
Before we start comparing these substrates any of them can be used to create a successful planted tank, some just give you better odds. In this article we are going to be talking about sand/gravel, clay based, dirted tanks and aquasoils.
Gravel & Sand
So let's start with sands and gravel. These are considered “inert” meaning that they have no chemical properties so they cannot hold any nutrients in the actual grains. This makes sand and gravel less useful in terms of feeding your plants and helping them grow. Nutrients can collect between the gaps but this makes it more luck based for your plants to find them. Between sand and gravel I have found it easier to plant into sand due to its small grain size. Since gravel is so heavy it is hard to plant and since the gaps are much larger it is harder to get the plant to hold in.
"A Strong Foundation Is The Key To Creating Long-Term Success."
Clay based substrates are things like eco-complete or fluorite. These come containing a high amount of iron usually from the material they are made from. They also have the ability to hold nutrients making them a decent choice for beginners but dirt and aqua soils do a much better job at this. A common complaint with fluorite is it makes a lot of dust when initially setting up the aquarium.
Dirted tanks are made by placing a small layer of dirt with a layer of (usually) sand over the top. Dirt contains a lot of nutrients making it super useful for plants but because of this if too much dirt is used it can cause algae in the early stages of your tank. There are lots of videos on youtube in how to deal with this. Dirt also has the ability to collect and hold more nutrients for your plants making it very useful if you want to keep the tank up super long term. The only problem with these tanks is they typically make massive messes when moving plants around. This is because dirt is pulled up through the sand and those nutrients get into the water.
Lastly is aqua soils which are the most used substrate in aquascapes. Some examples of common ones are Tropica, Fluval Stratum, and ADA Amazonia. They all have very similar properties that make them very useful. They all have small amounts of ammonia in them allowing for a fishless cycle. If you plan to add these to an existing tank ammonia spikes can be avoided by frequent water changes (every 2-3 days about 50%). Another factor is their ability to hold nutrients really well. They hold them just as well as dirt but they come without the mess. Aqua soils also are designed to make planting easy; they are very light allowing plants to not be damaged while planting. They are also very porous making rooting more easy. The only real downside is that aquasoils should be replaced about every 2 years because it can break down and lose its effectiveness.
That was a lot of information but hopefully it will help you determine what's best for you. I personally always spend the little extra for aquasoil but I know many people who have had success with all 4 of these substrate categories!