Aquarium Substrate - Planted Tank Mates
Aquascape substrate with live plants.

Aquarium Substrate

Overview

Selecting the aquarium substrate for your planted tank can be fun but also a little tricky.  In addition to the size and color, there are many things to consider including placement and inhabitants.  If you’re creating a planted tank with a carpet foreground, you’ll need a nutrient rich substrate.  If you’re planning a guppy tank with a few stem plants, gravel and sand may be just fine.  Got plecos and bottom feeders in your set up? Consider a finer substrate with rounded edges.  There’s no one size fits all and you can absolutely mix different types of aquarium substrate within a single tank.

Inert aquarium substrate in guppy tank
Inert Aquarium Substrate in Guppy Tank

Substrate Types

Even though there are so many types of substrates on the market, it all breaks down to 1 of 2 categories.  Is it an Inert or Active substrate?  

Inert substrates are typically sand, gravel and clay types.  They provide no nutrients to plants and they are poor at retaining it.  Although not impossible, it’s very difficult to create a grassy, carpet landscape with an inert substrate.  You can, however, grow certain stem plants and water column feeding plants. Supplement with root tabs and liquid fertilizers to keep plants healthy and alive.

Gravel inert substrate with aquarium plant tied to rock
Gravel inert Aquarium Substrate – available on Amazon

Active substrates are typically the manufactured type that’s designed specifically for freshwater aquariums.  Organic potting soil is also an active substrate, though not as popular.  In addition to being nutrient rich, active substrates generally have a high CEC content, which is the ability to retain nutrients in the soil.  Active substrates are generally more expensive and they’ll ultimately require some root tab and liquid fertilizer supplementation.  

Active substrate in planted tank
Active Aquarium Substrate – available on Amazon

Popular Brands

Everybody in the aquascaping world has heard about the nutrient rich ADA Aqua Soil.  This is considered the Cadillac of aquarium substrates and will give immediate success to any landscape.  It does lowers the PH and leech ammonia in the beginning, so don’t add livestock right away.  It will also break down over time in which you’ll need to supplement with root tabs or slowly replace.

Active aquarium substrate in a heavy planted tank.
Active Aquarium Substrate in Heavy Planted Tank

Fluval Stratum is nutrient rich like Aqua Soil, but it boasts the ability to retain a stable PH.  This is a great option for planted tanks with shrimp.

Seachem Flourite is another common name that comes around.  Although it’s manufactured to look like Aqua Soil, it’s actually a clay-like gravel and an inert substrate.  This inert substrate, however, has low CEC qualities and can retain nutrients, but nothing that can create a carpet foreground.  Many have praised this soil for its ability to retain its shape and not break down for 6-8 years.

Eco-Complete is another popular name that comes around.  It’s nutrient rich but has a rock, gravel-like appearance.  It’s much coarser than Aqua Soil and can have sharp edges.  This is great for guppies or middle to top dwelling fish, but not ideal for bottom dwellers like corydoras.

Coarse aquarium substrate with sharp edges and a juvenile pleco resting on top.
Coarse Aquarium Substrate with Sharp Edges

All Things Considered

Inert substrates are great if you have plants that feed through the water column and middle – top dwelling fish.  Active substrates are ideal for heavily planted tanks with root feeding plants.  Active substrates will also break down over time and require supplements and or replacement.  All substrates may initially cloud the water and alter the conditions, so plan in advance and proceed with caution. 

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