# How diligent should one be in removing mulm?



## cralz (Mar 11, 2012)

Every week during my water change, I vacuum up most of the mulm I can see (it collects around/on my driftwood, some rocks). A little while ago I had to lift up a piece of driftwood to find a hiding fish, and noticed there's a fair amount of mulm underneath.

Should I move hardscape in order to get rid of mulm? Or is it alright to leave it? I don't really like the idea of moving stuff around all the time, which likely disturbs some of my plants.

My tank is fully cycled, consistent 0 ppm ammonia/nitrite readings, if that makes a difference.

Thanks in advance to any replies.


----------



## mistergreen (Dec 9, 2006)

Remove what you see is fine.


----------



## if_fishes_were_wishes (Jul 29, 2007)

I get what I can once a week with the gravel vac without moving anything in my 55. I have a piece of driftwood that just stays put but I do go around it. You don't want pristine clean gravel - some mulm is good for the plants.


----------



## radioman (Oct 29, 2007)

I try to get what I see which is pretty much what is in the front of the tank and leave the rest.


----------



## LB79 (Nov 18, 2011)

Get all you can without moving stuff. A little bit is fine left in the tank until next water change.


----------



## TwoTacoCombo (Apr 13, 2012)

The top of my substrate is visibly clean. I've got plenty of flow between 2 filters and a Koralia, and a fierce gang of amano and yellow neos that keep the place tidy. If you're getting buildup of crud, try one or both of these things to help keep up appearances. I've found that trying to clean the gravel manually kicks up more muck than it removes, so I aim the flow to unsettle it and let the filters do most of the work.


----------



## Complexity (Jan 30, 2008)

While I agree that you should not be moving things around to clean up the mulm, I am also concerned as to whether you may have an excessive amount of mulm building up. Your filters should be able to kick most of the mulm into the water column and carry it to the filter intakes. If they're not doing a good enough job of this, then you may be getting too much of a build up in the tank.

So I think it's important to first double check whether the amount of mulm you're getting is a normal amount or an excessive amount. Only then can it be determined if you should do anything about it.

What substrate are you using? Some substrates allow the mulm to filter down into the substrate while others hold the mulm on top of the substrate. Sand, for example, will hold the mulm on top because sand is such a fine grain. There are no gaps in between the grains to allow the mulm to fall into. Larger substrates, such as Eco Complete, have large gaps that readily allow the mulm to fall into. This way the mulm filters deeper and deeper into the substrate, breaks down, and is then used by the plant roots. As a result, substrates with larger grains will _appear_ cleaner on the surface.

Also, what filter(s) are you running? Do you see any movement of the plants? Does the water flow pick up the detritus into the water column or does everything just drop to the bottom and sit there?

How heavily planted is the tank? Plants in a tank can act as obstacles to the water circulation, foiling the efforts of the filters to move the detritus to the intake screens. The more heavily planted the tank, the greater the need for circulation and filtration, especially if the plants are tall.

In general, it is true that you should not need to take special lengths to vacuum up the mulm. A gentle wave of the vacuum hose above the substrate should be all that's needed at the most. However, if you're getting an excessive build up of mulm, you need to take corrective measures so you don't end up with too much of it piling up, raising your organic load higher than what is healthy.


----------



## Diana (Jan 14, 2010)

Leaving some mulm is not a problem, but if for whatever reason you need to medicate the tank do an extra thorough job of vacuuming. Some meds start to work by latching onto almost any sort of organic matter, including mulm. Obviously this would leave less medication free to find the disease organisms. 

Sand, depending on the size of the particles can allow the finest mulm in between the grains. To clean sand without removing it from the tank takes a bit of a trick, but can really help clean it:
Hold the vacuum at enough of an angle that some of it is above the substrate surface, and is still sucking in water without substrate, and some of the tube is just tucked into the sand enough to disturb the sand without picking up too much. Hold your hand over the outlet tube in a way that you can pinch it off to stop (or almost stop) the water flow, just in case sand does get picked up too high. 

To clean between the plants thinner tubing, like air tubing or vinyl tubing that is just a bit larger will work. You do not need to have the wider siphon tube attached. I will sometimes use tubing with my hand near the end and a finger ready to close of the end that is in the tank. Curious fish often investigate the tube, and the flow is surprisingly strong. 

Another way to slow the flow if you are siphoning into a bucket is to raise the bucket so the siphon is not falling so far.


----------



## HD Blazingwolf (May 12, 2011)

Lol strong siphon.. i had a rainbowfish go for a ride down a 1 inch vinyl tubing hose one day. They usually stay away but this one was feeling froggy. He went in head first.
He survived with little more than a scratch. Recovery lasted maybe a week? I havent seen the mark on him in weeks and i took no extra steps to medicate


----------



## proaudio55 (Oct 20, 2011)

I don't usually have much so I just leave it all in the tank. With the auto water changer I have, it only skims off the surface and everything else remains. It hasn't caused any problems thus far...


Decaying plant matter returning nutrients back into the water column.








http://www.plantedtank.net/forums/pHosting.php?do=show&type=f&id=10682&title=Decaying_leavesb.jpg


----------



## Complexity (Jan 30, 2008)

I'd clean up those decaying leaves. I don't think it's good to leave that much decaying plant matter sitting in the tank.


----------



## proaudio55 (Oct 20, 2011)

eah, I've got a bubbler going for the loaches and nitrates always measure 0ppm. I haven't had any problems thus far


----------



## Complexity (Jan 30, 2008)

proaudio55 said:


> nitrates always measure 0ppm.


Are you sure you meant to say nitrates?


----------



## proaudio55 (Oct 20, 2011)

Complexity said:


> Are you sure you meant to say nitrates?


Yepper, I've got an auto water change system that flushes so much fresh water through every week that the water is basically "too clean". 0 Ammonia, 0 Nitrites, and 0 Nitrates. 

Thinking about it, I should probably turn that down some, just so I don't wear out my RO system-filters prematurely. 

Regardless, in a reasonably stocked 72 gallon tank with lots of plants, a little rotting organic matter has never caused me any problems.


----------



## Complexity (Jan 30, 2008)

For a planted tank, 0 nitrates isn't healthy. You need to do something to increase the nitrates because the plants need them as one of their major ferts. I agree, it sounds like you have your tank "too clean". I'd still remove the dead plant matter, but that's just me. We don't have to maintain our tanks the same way. That's one of the great things about this hobby. As long as it works for you, that's all that matters. :smile:


----------



## GraphicGr8s (Apr 4, 2011)

You call it mulm I call it fertilizer. 

What's a water change?


----------



## HD Blazingwolf (May 12, 2011)

you call it mulm, i call it biological oxygen demand.
what's an unhealthy fish? the whole reason many of us take up this hobby?

not that i't can't work that way, but mulm reduces bio available oxygen. so do decaying leaves and all other decaying matter.


----------



## wkndracer (Mar 14, 2009)

HD Blazingwolf said:


> you call it mulm, i call it biological oxygen demand.
> what's an unhealthy fish? the whole reason many of us take up this hobby?
> 
> not that i't can't work that way, but mulm reduces bio available oxygen. so do decaying leaves and all other decaying matter.


wwwhhhhaaatttt???? 
New term for me here; 'bio available oxygen' help if your so inclined plz.
Bio available oxygen is not a term I have ever read. From sport fishing magazines and books about plotting fish migration patterns to Walstad's book on natural aquarium keeping. Dozens and dozens of lake studies over the years and I'm clueless as to what this would refer too. 

*Dissolved Oxygen as an Indicator of Bioavailable Dissolved Organic Carbon in Groundwater.*

_Concentrations of dissolved oxygen (DO) plotted vs. dissolved organic carbon (DOC) in groundwater samples taken from a coastal plain aquifer of South Carolina (SC) showed a statistically significant hyperbolic relationship. In contrast, DO-DOC plots of groundwater samples taken from the eastern San Joaquin Valley of California (CA) showed a random scatter. It was hypothesized that differences in the bioavailability of naturally occurring DOC might contribute to these observations. This hypothesis was examined by comparing nine different biochemical indicators of DOC bioavailability in groundwater sampled from these two systems. Concentrations of DOC, total hydrolysable neutral sugars (THNS), total hydrolysable amino acids (THAA), mole% glycine of THAA, initial bacterial cell counts, bacterial growth rates, and carbon dioxide production/consumption were greater in SC samples relative to CA samples. In contrast, the mole% glucose of THNS and the aromaticity (SUVA254) of DOC was greater in CA samples. Each of these indicator parameters were observed to change with depth in the SC system in a manner consistent with active biodegradation. These results are uniformly consistent with the hypothesis that the bioavailability of DOC is greater in SC relative to CA groundwater samples. This, in turn, suggests that the presence/absence of a hyperbolic DO-DOC relationship may be a qualitative indicator of relative DOC bioavailability in groundwater systems._

_Francis H. Chapelle, Paul M. Bradley, Peter B. McMahon, Karl Kaiser, Ron Benner. Article first published online: 24 JUN 2011_

I play around a lot with NPT type systems and high volumes of organic content in the substrate. Doing that I've read a bunch on the topic. While most bacteria do use O2 without going to the extreme of a cesspool what the heck is the concern?

Living is learning and I would be grateful if you'd share.

OP, (imo) a little mum is fish provided food for plants. 
Whats old tank syndrome? I have a tank with a gravel mix that's been wet for at least 24yrs without a gravel cleaning. I wouldn't be worried much about it.


----------

