"The Pasta Sauce Analogy" and Aquatic Substrates...

We talk about soem weird things around here, don't we? 

I admit, we have some rather "unorthodox" approaches to stuff. However, I think. a lot of what we are doing here is becoming more "mainstream" all the time..Or, at least, a lot of this stuff is getting more consideration than it has in the past!

Back in 2015, we talked about the idea of "substrate enrichment" in botanical-style aquariums. In other words, adding botanical materials to the more traditional substrates of sand, etc. Now, at first glance, this idea seems rather "normal" in many respects. I mean, planted aquarium enthusiasts have been adding various supplements to their substrates for decades, with the intention of providing beneficial trace elements and nutrients for plants.

Yet, we're talking about enriching the substrate for the purpose of providing tannins, humic substances, and nutrition- for microbial and crustacean life forms that could reside in the substrate. Not primarily for aquatic plants.

When you examine the substrates found in many natural habitats, they often appear to be a mixture of a variety of materials, including sands, sediments, muds, clays, and botanical materials. These materials not only look different- they function in unique ways, not only influencing the water chemistry, but the biology and ecology of the aquatic systems as well.

Now, in Nature, there are numerous factors which contribute to the composition of substrates in wild aquatic habitats, including geology, the flow velocities of the body of water, the surrounding topography, the seasonal variations in water level (ie; inundation/dessication cycles), and accumulation of materials from the surrounding terrestrial environment.

Nature utilizes almost everything at her disposal in order to create and maintain aquatic ecosystems. So, why do we as hobbyists, who want to create the most realistic approximations of wild habitats possible, just sort of "mail it in" when it comes to substrate? I mean, just open a bag of _____________ sand or whatever, and call it a day and move on to he more "exciting" parts of our tank?

I think we just rely on the commercially available stuff and that's that.

Now, in defense of the manufacturers of sands and gravels for aquarium use- I love what they do, and what they have available. These items are of generally excellent quality, provide a wide range of choices for a variety of applications, and are readily available.

However, IMHO, they are a great "starting point" for creating more dynamic substrates for our aquariums. Kind of like tomato puree is to pasta sauce...a beginning! Sure, you can use just the puree and enjoy it as your sauce, but isn't it always better to add a bit of "this and that" and build on the "base"to create something better?


(Damn, it's 7:00AM here in L.A., and now I'm craving Penne...WTF?)

That, in a nutshell, is my theory of aquarium substrates. 

We can do a bit better.

We will do better with the imminent first release of our "NatureBase" substrate line!

Okay, back to the wild for a second...Let's look at how natural substrates form.

Now, in many of the tropical regions we admire, the basic substrate is often referred to simply as "fine, white sand" in most scientific papers- typically, but not necessarily a silica of some sort. And of course, other locations have slightly larger grain sizes of other pulverized stones and such. Still others are comprised of sediments which wash down from higher elevations during seasonal rains.

Deep rivers will typically have different substrate compositions than say, marginal streams or floodplain lakes, or even flooded forests. In the Amazon region, a huge percentage of the sediment and materials which comprise the substrates are from the Andes mountains, where they are transported down into the lower elevations by water flow.

This has huge foundational impact on the chemistry of the waters in the region. This process builds the fertile floodplain soils along Andean tributaries and the main stem of The Amazon.

There is a whole science around aquatic substrates and their morphology, formation, and accumulation- I don't pretend to know an iota about it other than skimming Marine biology/hydrology books and papers from time to time.

However, merely exploring the information available on the tropical aquatic habitats we love so much- even just looking long and hard at some good underwater pics of them- can give us some good ideas!

First off, in some areas- particularly streams which run through rain forests and such, the substrates are often simply a terrestrial soil of some sort. A finer, darker-colored sediment or soil is not uncommon. The water chemistry- indeed, "blackwater" itself, is based on the ionic, mineral, and physical concentrations of terrestrial materials that are dissolved into the water. And the degree to which these materials disperse into the aquatic environments vary based on water velocities, time of year, and other factors, as touched on above. 

Meandering lowland rivers maintain their sediment loads by continually re-suspending and depositing materials within their channels- a key point when we consider how these materials remain in the aquatic ecosystems.

Okay, I could go on and on with my amateur, highly un-scientific review of substrates in Amazonia and elsewhere, but you get the point!

There is more to the substrate materials found in Nature than just "sand." That's the biggest takeaway here! So, as hobbyists, we have more options and inspiration to to draw on to create more compelling functional substrates in our aquariums!

What that means to us is (taking into account the "pasta sauce analogy", of course) is that we should consider mixing other materials into our basic aquarium sands. For example, you could mix aquatic plant soils into you sand. You could experiment with materials such as clay, or other mineral/plant-based components of varying particle sizes. 

Obviously, your substrate will look a lot different than the "typical" aquarium substrate when you start mixing materials. Your overall aquarium will, too. And that's a good thing, IMHO. I played around with this a lot in my office brackish water Mangrove aquarium, where the substrate played an integral functional role in the aquarium, as well as an aesthetic one...

If you start with one of our "sedimented" substrates, which already is intended to mimic the look and characteristics of natural aquatic substrates, you're already a little ahead of the curve. However, you can apply this idea to just about any type of aquarium substrate, 

A combination of finely crushed leaves, bits of botanicals, small twigs, etc. can form the basis for a more "biologically active" and even productive substrate. As these materials break down, they are colonized by fungi and biofilms, and impart  tannins, lignin, and other sources of carbon into the water to fuel a variety of microbial growth.

And of course, larger crustaceans and even fishes will consume the organisms which live in this "matrix", as well as possibly consuming some of the detritus from the decomposing leaves themselves.

Its a very different looking- and functioning- substrate, for sure. At the risk of sounding too commercial here, suffice it to say, we have a whole damn section on our site called "Substrate Additives" for the very purpose of facilitating such geeky experiments! 

This stuff is THAT interesting to me...It's wide open for lots of experimentations, evolutions, and evenbreakthroughs.

Look to Nature, again.

Now, of course, you're running an aquarium, not managing a stretch of open wild river or stream. Duh. The dynamics of closed systems are a bit different! However, the forces of Nature and Her "laws" will  always apply. It's up to us as aquarists to make the effort to understand them and work with them, instead of against them.

You won't see a "pristine" substrate. Rather, you'll see the usual suspects- biofilms, fungal growths, decomposing botanical materials, and the accumulation of some detritus. 
That's the stuff you want. IMHO. 
And, if you apply some of the other ideas that we've talked about, such as "pre-stocking" with organisms like copepods, worms, crustaceans, Paramecium, etc., you'll create a microhabitat teeming with life- one that will have profound benefits for your aquarium overall.
A mix of materials of different sizes on and in the substrate creates the "interstitial" spaces that benefit many small organisms, functioning as protection and breeding areas. You might say that, to some extent, an "enriched" or "enhanced" substrate functions as sort of a "refugium", providing protection for many beneficial creatures to grow and multiply.

You could create a bit of a mess if you're not too fastidious about the overall husbandry. You obviously can't overstock, overfeed, etc. Basic aquarium husbandry stuff. Yeah, it's entirely possible to create a smelly, anaerobic pile of shit on the bottom of your aquarium if you're lazy!

I've maintained these types of substrates over very long periods of time without any issues. Period. Sure, there is always the remote chance that you may nuke your entire fucking tank, of course, if you're not careful- but I think it highly unlikely if you follow basic tenants of aquarium husbandry, otherwise! I've played with this idea for almost 16 years without a single issue.

"Gee Scott- thanks! Another way to kill my fishes, courtesy of your weird ideas!"

Okay, it's not that weird. And really, not that dangerous.

I just don't want some flat-out beginner, heading home from the LFS with a brand new nano-sized aquarium, complete with a "Sponge Bob" bubbling ornament, purple gravel, and 20 Neon Tetras to go online, find our site, see some pics, and dump 12 ounces of crushed leaves, 3 ounces of "Substrate Fino", and a bag of oak twigs into the gravel and expect some sort of miracles, you know?

You need to move forward with caution. However, you needn't be afraid. You simply need to observe very carefully, have reasonable expectations about what will happen, and you have to accept an entirely different look that accompanies the function.

Typically, when "enriching" your substrate with botanical materials, you'll see an initial "surge" of the aforementioned biofilms and such, ultimately subsiding to a sort of "baseline" of a little bit of stuff in and among the substrate. WARNING: It will NEVER look "pristine" or "competition sterile." Get that idea out of your head immediately. That's only one "standard" for assessing what a "healthy" substrate is. 

Your system WILL look much, MUCH more natural, dynamic, and altogether unique. Consider once again that, when you're incorporate decomposing botanical materials, not only are you adding to the biological load of the aquarium, you will be fostering the growth of beneficial microorganisms, like bacteria...Could this lead to enhanced denitrification or even "fermentation" in deeper substrates, which enhance the overall water quality? And what about it's potential as a "mulch" of sorts for aquatic plant growth?

It's interesting, exciting, and potentially game-changing to utilize varying materials to "enrich" your substrate in a variety of ways. And it's all big, fun, incredible experiment. It all starts with a few basic materials...and can become as rich and diverse as you care to make it.

Pasta sauce, indeed.

Stay creative. Stay excited. Stay curious. Stay diligent. Stay thoughtful...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Scott Fellman
Scott Fellman


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