Mulm, detritus, and debris

[Onoma1]

To mulm or not to mulm. That is the question.

I have a largish patch of mulm, moss and debris in my 120cm ( I need to confess). This wasn't the plan for this particular medium energy tank. However, its now shrimp heaven, bits of buce and anubias are now developing in it and the smaller fish, and nano catfish seem to love it.

I cultivate this in my other low energy tanks, however hadn't planned for this in this particular tank.

Now I know that for some this stuff is the source of all evil. Evil in this case being BBA and other persistent algie and other nasties. It should be removed with a turkey blaster ASAP.

Others see it as a positive development and an essential part of an ecological approach to planted tank development.

I wondered what other people thought. Does this material have a place in medium or high energy planted aquarium?

I have (shamelessly) shared a picture of my patch below:

Just to clarify this is to the middle/right side of the picture above!

The whole tank (for context).

 

[Tyko_N]

I like it, I have a corner where quite a bit of mulm collects in my paludarium and I leave it in, mainly because the fish seem to enjoy it so much. I'm kind of skeptical about it causing algae as well, "real" mulm should be fairly inert, containing the parts of plant remains that's the slowest to decompose, like lignin and cellulose, so only contributing very limited (if any) nutrients. Although it's a big difference between having the real stuff of hard to decompose plant matter, like it seems you have, compared to just piles of old fish poo, the latter I can definitely see causing issues.

 

[_Maq_]

piles of old fish poo, the latter I can definitely see causing issues.

What if the causal chain works differently? If feces accumulate, it suggests that decomposers are neglecting their work. Why? That is the question...
I'm used to think about microbes in broad sense, incl. fungi and algae. I also believe that well-established bacteria can to a degree suppress algae. From this we may deduce that accumulating feces => weak bacteria => algae benefit from it. What do you think?

picture of my patch below:

What does your substrate consist of? Only soft silica sand?

 

[Tyko_N]

From this we may deduce that accumulating feces => weak bacteria => algae benefit from it. What do you think?

I think you're on to something here. A healthy decomposer community should not only make the nutrients of what they break down less available, but also remove some nutrients from the water column to allow their own growth. In saltwater circles some people deliberately dose a carbon source to their tanks, and as the bacteria and co feeds on this they take up nitrogen and phosphorus from the water, which is maybe equivalent? For this effect in freshwater you would need detritus with high carbon but low nitrogen levels though, like dead leaves (and maybe herbivorous pleco poo?), rather than the more nutritious left overs of more predatory fish.

 

[dw1305]

Hi all,

I have a largish patch of mulm, moss and debris in my 120cm ( I need to confess). This wasn't the plan for this particular medium energy tank. However, its now shrimp heaven, bits of buce and anubias are now developing in it and the smaller fish, and nano catfish seem to love it.

I think <"it is a good thing">. My friend from Bristol, the late Bob Marklew, <"had mulmy tanks"> and he was an incredibly good fish keeper.

In saltwater circles some people deliberately dose a carbon source to their tanks, and as the bacteria and co feeds on this they take up nitrogen and phosphorus from the water, which is maybe equivalent

It is slightly different in that they want to keep <"REDOX values as high as possible"> and don't have access to higher plants etc.

I'm kind of skeptical about it causing algae as well, "real" mulm should be fairly inert, containing the parts of plant remains that's the slowest to decompose, like lignin and cellulose, so only contributing very limited (if any) nutrients.

<"I think that is probably"> the real point, <"not all organic debris"> is equal.

Is there any advantage to its complete removal, I'm pretty sure that answer is "no", and that if you could get water entirely devoid of DOC it would impinge on fish health. There is quite a lot of <"scientific research in this area">, although @jaypeecee may not like the <"shades of grey"> aspect to it.

Personally I think that the <"BOD concept"> is more useful, which is why you <"can have tanks full of structural leaf litter and dead wood">, but with very high water quality.

cheers Darrel

 

[Bradders]

@Onoma1 - out of interest, is that just the camera making your water look very milky?

 

[Onoma1]

@BRJP1 Yep it's my lousy camera skills while using my mobile making it look milky and generally a bit washed out. It was a quick snap after feeding the fish. In retospect, both photos look awful 😱 I need to take another decent one ASAP with a better camera and brush up on my skills ...

@_Maq_ It's ADA sand mixed with two other types of cheaper aquarium sand. In the last scape I added ADA on top of the other types of sand. This is now mixed and has been reused. The sand covers a number if bags of John Innes Number 3. I have liberally sprinkled osmacote under the sand in the heavily planted areas.