Breaking from tradition...

There are some things that are almost "universal constants" in the aquarium hobby. You know, routine husbandry tasks: Cleaning filters, feeding, quarantine, and water exchanges.

Yeah. I said it.

Water exchanges.

That dreaded pairing of words that hobbyists worldwide for generations have went to great length to avoid. That simple, yet somehow off-putting process that has spawned numerous "inventions" over the decades promising to "reduce or eliminate" them. 

It's literally the aquarium husbandry equivalent of making your bed. No one really likes to do it, but the benefits are significant and well documented. 

So, we do them.

Now, I personally have always been a firm believer in some forms of nutrient export being employed in every single tank I maintain. Typically, it's regular water exchanges. Not "when I think about it', or "periodically", mind you.

Nope, it's weekly. 

It's like my habit. Part of my schedule. A "thing" I do.

Now, I'm not saying that you can essentially disobey all the common sense husbandry practices we've come to know and love in the hobby (like not overcrowding/overfeeding, etc.) and just change the water weekly and "everything's good."

What I am saying is that incorporating regular water exchanges into your system gives you the ability to dilute any potential accumulating organics/pollutants before they become a significant negative impact on water quality.

They simply give you a bit of a "buffer", essentially. A margin for "error."

I don't need to go into the numerous well-trodden reasons about why water exchanges are a good thing in the aquarium. However, I do need to give us a collective whack upside the head and encourage each and every one of us to think about this stuff from the perspective of an overall closed ecosystem. Think about what the nitrogen cycle is and does, and think about the impact of inputs and exports into and out of our closed systems. 

And I might have some thoughts here which may make water exchanges perhaps just a bit less of a mental- and physical- burden on you.

Hear me out.

You know all of the stern admonitions you receive about "removing detritus" in water exchanges?

Well, let's consider blowing up that argument just a bit and leaving some of it in the tank!


First off, let's look at what this stuff actually is. In the aquarium context, the definition of "detritus" is pretty telling:

"detritus is dead particulate organic matter. It typically includes the bodies or fragments of dead organisms, as well as fecal material. Detritus is typically colonized by communities of microorganisms which act to decompose or remineralize the material." (Source: The Aquarium Wiki)


It's one of our most commonly used aquarium terms...and one which, well, quite frankly, sends shivers down the spine of many aquarium hobbyists. (translation: "Leaving it in will assure Doomsday for your aquarium! You're f ----d!")

And judging from that definition and the mindset we've cultivated about detritus for the last, oh, century-  it sounds like something you absolutely want to avoid having in your system at all costs. I mean, "dead organisms" and "fecal material" is not everyone's idea of a good time, ya know?

Yet, when you really think about it, "detritus" is an important part of the aquatic ecosystem, providing "fuel" for microorganisms and fungi at the base of the food chain in tropical streams. In fact, in natural blackwater systems, the food inputs into the water are channeled by decomposers, like fungi, which act upon leaves and other organic materials in the water to break them down. 

And hey, don't these decomposers serve to break down leaves and provide a secondary food source for many fishes?

Oh, snap- they DO!

Wouldn't it make sense to have larger populations of some of these organisms available to our fishes at all times in the aquarium to supplement our artificial diets? Could the fry-rearing system of the future be a tank with a big bed of decomposing leaf litter and a terrestrial soil substrate?


Think about the potential benefits of allowing some of this stuff to remain in your aquarium. 


Look at the natural habitats which our fishes come from; how they function...why they exist successfully.

Think about the organisms which feed upon it, their impact on the water quality, and on the organisms which fed on them. Then, think about the fishes and how they utilize not only the material itself, but the organisms which consume it.

Consider its role in the overall aquarium ecosystem...

Is detritus a "nutrient trap?" A place where water quality is slowly destroyed? A ticking time bomb that will bring down your tank?

Or is it...a place for fishes to forage in?

A place for larval fishes to seek refuge and sustenance in? Kind of like they do in nature, and have done so for eons. Yes, I know that we're talking about a closed ecosystem here, which doesn't have all of the millions of minute inputs and exports and nuances that nature does, but structurally and functionally, we have some of them at the highest levels (ie; water going in and coming out, food sources being added, stuff being exported, etc.).

I think we really need to think about our systems- particularly in the blackwater/botanical-style aquarium world- as little microcosms which replicate- at least on some level, some of the process which occur in nature to create a specialized but highly productive and successful- not to mention, dynamic- ecology. 

There is so much more to this stuff than buying in unflinchingly to generalized statements like "detritus is bad."

Most hobbyists don't have the time, inclination, or optimized system set up to take advantage of a small accumulation of this stuff. I understand that. However, with the importance of detritus in creating food webs in wild leaf litter communities, which we are now replicating to some extent in aquariums, could there actually be some benefit to allowing a little of this stuff to accumulate?

Or at least, not "freaking out" and siphoning up every single microgram of detritus as soon as it appears in our tanks?

I think so.


Is this another one of those long-held "aquarium truisms" that, for 90% of what we do is absolutely the correct way to manage our tanks, but which, for a small percentage of aquarists with the means, curiosity and inclination to experiment, could actually prove detrimental in some way?

You know, like the many thousands of us worldwide who keep blackwater, botanical-style aquariums, many field with aquatic plants lately?

There's usually very little for them to forage on in most aquariums, other than the occasional algal film (assuming they're herbivorous) or particle of uneaten food. Creating militant, "near sterility" in our aquariums, which do at least superficially resemble true ecosystems, might actually be detrimental in some way, right?

I mean, you're removing one component of a natural cycle and replacing it with a high-octane, "shotgun approach" substitute of just taking everything out. Wouldn't a more functionally stable system benefit from keeping this stuff in?


It's a mental shift.

A perspective of open-minded curiosity...and a willingness to look at things a bit differently and go beyond the usual and generally accepted ideas on stuff. It's not always pretty. It's not always right.

I'll give you that much.

I'll keep going for just a bit more before leaving it to you for contemplation...

Question: Are we actually making the management of aquariums more challenging by sort of "fighting" nature, and simply not thinking this through all the way? Doesn't nature, if left to her own devices, tend to keep excesses of all sorts more-or-less in check? 

Is there some advantage to allowing our aquariums to harbor a greater diversity and population of life forms, in order to have a more complete "functional capability?" Is this the road to an "out-of-control over-populated" closed system? DO we dare experiment? Or, is it simply more advantageous to buy that new, high-powered canister filter that holds six liters of carbon, and create pristine, "drinking-water quality" conditions in the tank and call it a day?

No, I don't think so.

I think that there is some merit in the idea of leaving a bit of detritus in the system- say, in the leaf litter bed, to help "fuel" the fungal and microorganism growth that forms the basis of our little ecosystems? I mean, think of some possible benefits to our aquariums. Having a more complete assortment of fungi and microorganisms could lead ultimately to a more stable, more efficient aquarium...

So, next time you begrudgingly reach for the siphon hose...think about how this whole little "closed aquatic ecosystem thing" works.  Another consideration which address some of the most fundamental, long-held beliefs and practices in aquarium-keeping, might help us make not only more "mental shifts", but true breakthroughs as we rediscovery the utility of the elegant, yet "complex simplicity" that nature has engineered over the eons.

Ponder that the next time the calendar says "Water exchange day!"

A "clean" break from tradition...or just supporting nature in a more productive, more beneficial, and more efficient manner? 

Bold aquarists wanted.

Stay curious. Stay excited. Stay diligent. Stay observant...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



Scott Fellman
Scott Fellman


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