Mission: Mud... A place for Freshwater, brackish, reef geekiness!

I'm sort of continuing my obsession with mud in aquarium substrates. For all of the "weirdness" about it, the use of mud and sediment seems to have so many interesting applications, aesthetic nuances, and potential ecological benefits for the aquarium.

Now, my experience with "mud" ( really, "sediments") starts with the reef aquarium world. Mud was one of those odd tangents that hit the hobby right around the “early 2000’s "refugium craze", and sort of faded quickly into the background. I am sure that part of the reason was a renewed obsession later in the decade with less biodiverse, more “coral-centric” systems, which eschewed substrates in general, specifically those which had the tendency to house competing biota! All of those factors- and a continued obsession with using high tech electronic pumps to facilitate ridiculous amounts of water movement within our aquariums sealed the fate of mud as a true “side show” in the reef hobby for the foreseeable future.

Well, did it? 

Now here we are, in the fading years of the 2nd decade of the new millennium, and I think that it’s time to resuscitate the idea of using mud in our  aquairums- reef  and otherwise- again in some capacity. And I’m thinking not JUST the refugium, in the case of reef tanks. I’m talking about the display! I know a lot of planted tank enthusiasts have used "mud" in so-called "dirted" planted tanks with much success, and I think there is more to it. My recent brackish-water obsession has seen me make liberal use of such sediments, and I'm thinking that there is much room for experimentation in other types of freshwater and- yes, reef aquariums.

Now, I realize that a lot of reefers will disagree with my thinking, and duly advise that sand and mud and sediment can become “nutrient sinks” and work against the smooth operation and long term prosperity of a reef. The operative word here, IMHO- is CAN. I mean, even water exchanges can be problematic if poorly executed, right? So I think it might be worth looking at how a well-managed mud/sediment/sand bed could help support a healthy, diverse closed reef ecosystem.

Now, if you go way back into the past (like 2005), you may recall some of the studies into various substrate depths and compositions (and plenums!) and their relative impact on mortality of animals in reef aquaria. Now, in all fairness, the test subjects were fishes and inverts like hermit crabs and snails, but the findings are nonetheless relatable, in my opinion, to reef tanks. Researchers Tonnen and Wee ran a lot of tests with different depths of substrate, ranging from very shallow to rather deep, and the results were quite fascinating, in my opinion. Interestingly, one conclusion was that “...the shallower the sediment, the higher the mortality rate, and you can't get much shallower than a bare bottom tank!"


 Again, that set of experiments had a lot of different variables, like the use of pretty coarse substrate in some setups (Not too many of us use that stuff!), and no real test using marine muds and sediments as the sole substrate in a reef setting. However, I think it is perhaps safe to say that the presence of a substrate itself in a reef tank doesn’t spell disaster for the inhabitants- be they fish, corals, or urchins…The reality is that a well-managed, carefully stocked reef tank should work under a variety of situations.

In a freshwater aquarium, I think that you'd have a lot more interesting possibilities, with plants and "complete" ecosystems being more commonly modeled.

We have offered a few different substrate "enhancement" materials, like "Fundo Tropical" and "Substrato Fino", which are perfect for just this purpose- and sort of mimic aspects of the function and appearance of wild aquatics substrates.

And of course, the cautions are warranted. A poorly maintained "muddy" or "sediment-heavy substrate, without some creatures present to stir up the upper layers, can prove problematic if detritus and organic wastes are allowed to accumulate totally unchecked, right? And there is the so-called “old tank syndrome” , postulated by aquarists who suggest that after some point in a aquarium system's "operational lifetime" (whatever that might be!) the bacteria population within the system (likely the sanded) is depleted somehow and/or no longer has the ability to keep up with the accumulations of organic waster products, and that phosphates and such are released back into the system.

Is that always the case? Do we have enough aquarium work under our collective belts to really make this conclusion?

Not sure.

I am probably being a bit biased, but I have a real problem with that theory.

I just don’t see how a well-managed aquarium declines over the years. I’ve personally maintained one reef tank for 12 years, and one freshwater tank for 16 years straight and never had these issues. Other aquarists have had similar- or better experiences, too. I’m not saying to nominate me for sainthood or anything, but I will tell you that I am a firm believer in not overstocking my tanks, utilizing multiple nutrient export avenues (protein skimming, activated carbon, use of macro algae/plants, and weekly water exchanges).

There is no magic there.

Okay, that being said, tanks with substrate, specifically fine sediment materials like mud and such, are not “set and forget” systems. You’ll need to be actively involved. And by “actively involved”, I mean more than tweaking the lighting settings on your LEDS via your iPhone). You’ll need to get your hands wet.

Which to me, is the best part of aquarium keeping!

The time has never been more appropriate. Time to look at some of these “niche” ideas with a new mindset- and a new appreciation for what they can accomplish!

Let’s hear your thoughts on the idea of mud/sediment, and how the best parts might be incorporated into a “second decade” twenty-first century aquarium- freshwater, brackish, or reef!

Stay bold. Stay curious. Stay engaged. Stay open-minded…

And Stay Wet.

Scott Fellman 

Tannin Aquatics 

Scott Fellman
Scott Fellman


2 Responses

Scott Fellman
Scott Fellman

December 26, 2020

Hi Arshad,

Thanks for the ind words! I’m crazy about muddy substrates, myself, so I’m glad I may have piqued your interest!

Welcome to “The dark side!”



December 25, 2020

Recently came across this article, brilliantly penned by Mr Fellman. I’m new to Tannin Aquatics but I’m thoroughly enjoying everything!

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