One challenge in planning for a new planted aquarium is determining how much substrate you need for your planted aquarium. It becomes challenging to compare various brands of substrate (that all come packaged with different volumes of product in each bag) and plan for the number of bags that your setup will require (and know the resulting total cost).
To help with this, I have created an Aquarium Substrate Calculator. You can enter the dimensions of your aquarium and the desired substrate depth, and it will calculate the volume of substrate you will need. I have made things uniform by making all volume calculations in Liters. One thing to note is the first user input to select a preference for inches or centimeters.
Select from the list of substrates, and it will tell you how many bags you need to purchase and the estimated total cost (in US dollars). You can modify the fields for ‘Liters per Bag’ and ‘Cost per Bag’ after they are populated if you have an updated price or product. The costs are based on the current price on Amazon (shipping costs are not included).
Concerning the desired depth, it can vary from 1 to 4 inches (2.5 to 10 cm) depending on the aquarium’s scale and the plants’ needs. If you are planning on a significant slope of substrate, you will have to visualize where the midpoint of this slope will be and make that point an estimated depth. I have an average depth of around 2.5 inches (6.4 cm) in our Fluval Spec V Aquarium.
The volume per bag and cost per bag in this substrate calculator are based on my research and, in the case of Up Aqua Aquasand, from a bag that I purchased for our tank. Below the calculator, I have more information on the substrates I have included in this calculator. Cost can vary greatly, especially when considering shipping for multiple bags of substrate. Feel free to check the cost for the number of bags and update the fields for a more accurate total.
- ADA Aqua Soil Amazonia – This has long been the standard for planted aquariums. It comes advertised by volume; in this case, it contains 9 Liters of substrate in each bag. It is also available in a 3-liter bag. The positives of Amazonia are that it is very nutrient-rich and subsequently offers excellent plant growth. The negatives are that it is so nutrient-rich that it can cause the ammonia to spike for the first month or so; this may require frequent water changes to keep ammonia levels safe. The other common disadvantage is that it turns into ‘mud’ or breaks down over time.
- ADA Aqua Soil Amazonia II – Very similar to Amazonia, but with a few changes to make it more beginner-friendly. ADA is a little fuzzy on the details, but I understand the substrate has fewer nutrients and does not have as big a problem with ammonia leaching at the start.
- ADA Aqua Soil Amazonia Light – Same characteristics as the Amazonia II (fewer issues with ammonia at the start) and in a lighter hue (more brown than black).
- Up Aqua AquaSand – This is the substrate I chose for our aquarium’s recent rescape. It is sold in 5 kg bags. I measured the volume as 4.4 liters. I have a review here.
- Seachem Flourite Black – This substrate is what I initially had in our nano aquarium. It is sold in a 7 kg bag. The Seachem website puts this bag at 5.3 Liters.
- I have not used Fluval Plant and Shrimp Stratum, but it gets good reviews from planted tank enthusiasts. It comes in 4.4 lb and 8.8 lb bags. I estimate that the 8.8 lb bags have a volume of around 5.4 Liters.
- CaribSea Eco-Complete – This is similar to fluorite. It is sold in a 20 lb (9.1 kg) bag. Eco-Complete is sold with some water already in it that supposedly helps to cycle your aquarium. This water throws off the conversion from mass to volume, but I estimate each bag has 5.9 Liters.
The good news for people setting up a Spec Aquarium, whether the smaller III or the larger V, is that one bag of whatever substrate you choose will probably be enough.