# Brown sludge after massive plant death



## HomeroThompson (Mar 15, 2020)

Due to a series of unfortunate events, I had to leave my home city for several months, and left my tanks under the care of a friend. They also had some unfortunate occurrences, and my tanks ending up being neglected. In particular, the floaters grew out of control, blocking all the light and resulting in the death of most of my crypts, Bacopa caroliniana, Wisteria, swords, among others. Rather surprisingly, the fish themselves were doing fine, which I assume is due to the floaters keeping the parameters in check.

Now, as a result of all the decaying plant matter, the substrate is covered in some kind of brown sludge:
























I've relocated the livestock and an trying to get rid of the sludge. However, this is not very simple, as siphoning the gravel would disturb the soil layer and create an even greater mess. My reasons for getting rid of it were mainly aesthetic, i.e. it's not a pretty sight. But, given the difficulty of removing it, I'm wondering whether keeping the sludge would be harmful. Does anyone know whether it will go away on its own? I imagine further decay which then seeps through the gravel (Ecocomplete, for reference). 

Is the tank salvageable? Or do I need to restart everything?


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## johnwesley0 (Feb 23, 2021)

Depends on how you define _salvageable. _Depend on how you define _restart. _The sludge itself might be full of valuable nutrients. How much water are we talking about? Can it just be siphoned off into a few buckets while you rearrange the substrate?


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## mistergreen (Mar 3, 2007)

You can hover a siphon above the substrate to siphon out the mulm. This could take several sessions.


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## HomeroThompson (Mar 15, 2020)

johnwesley0 said:


> Depends on how you define _salvageable. _Depend on how you define _restart. _The sludge itself might be full of valuable nutrients. How much water are we talking about? Can it just be siphoned off into a few buckets while you rearrange the substrate?



By _restart_ I mean "empty the tank, substrate and all, buy new dirt, start from scratch". I suppose the definition of _salvageable_ in this context is whether I can avoid restarting, and can grow plants in this conditions.

Not a lot of water, 10 gallons. I'm been running a small pump to make the sludge fly all over the place so that I can catch it with a net. I'm also running a small HOB filter to catch some of the debris.



mistergreen said:


> You can hover a siphon above the substrate to siphon out the mulm. This could take several sessions.


That's what I've been doing, but it's hard to not suck up the substrate with it; Ecocomplete is very light. I suppose I'll keep at it.


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## johnwesley0 (Feb 23, 2021)

You're going to wind up doing a lot of siphoning no matter what. If it's mulm, it's harmless and may even be a valuable source of certain minerals for the surviving plants. I see no reason why you can't siphon out the water, save most of it it in a couple of buckets and mix a little mulm/gravel together with the present substrate, making sure it's not too thick, throw out what you don't need and give it a new cap.


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## mistergreen (Mar 3, 2007)

HomeroThompson said:


> That's what I've been doing, but it's hard to not suck up the substrate with it; Ecocomplete is very light. I suppose I'll keep at it.


Attaching a big tube to the hose will help like in a python water changer. It will lift the lighter mulm but not the heavier substrate.


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## HomeroThompson (Mar 15, 2020)

johnwesley0 said:


> You're going to wind up doing a lot of siphoning no matter what. If it's mulm, it's harmless and may even be a valuable source of certain minerals for the surviving plants. I see no reason why you can't siphon out the water, save most of it it in a couple of buckets and mix a little mulm/gravel together with the present substrate, making sure it's not too thick, throw out what you don't need and give it a new cap.


I'm not sure I follow. If I remove the cap to make a new one, wouldn't the soil layer be disturbed?


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## johnwesley0 (Feb 23, 2021)

HomeroThompson said:


> I'm not sure I follow. If I remove the cap to make a new one, wouldn't the soil layer be disturbed?


Yes. Remove the old cap. What have you got to lose? Don't think of your substrate as _substrate_. Think of it as dirt and proceed accordingly.


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## HomeroThompson (Mar 15, 2020)

johnwesley0 said:


> Yes. Remove the old cap. What have you got to lose? Don't think of your substrate as _substrate_. Think of it as dirt and proceed accordingly.


My main objection is that the dirt tends to not smell great once it's uncovered, and I'm not in a place where a mess can be easily cleaned out.


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## dwalstad (Apr 14, 2006)

The sludge is just microorganisms happily growing in a tank full of nutrients from the decaying plant matter. I'm guessing that bacteria are stuck to the gravel particles (i.e., Eco-complete?) with their sticky biofilms. So it's going to be virtually impossible to remove the sludge without sucking up the gravel. 

The fact that the fish are alive and the dirt doesn't smell suggests that the tank is not a lost cause. I would add more plants to replace those that were lost. (Tank looks "underplanted" to me.) Then, I would add a major clean-up brigade (shrimp, snails, algae-eating fish, etc). A couple Chinese Algae Eaters might clean up that gravel in a couple days? You'll have to experiment with what works best. It may take awhile to get rid of the sludge, but it is not impossible. 

Keep us posted!


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## Endler'sGame (Aug 25, 2020)

What about a thin layer of new gravel to cover the mulm? Mulm is good stuff for the plants but I do understand why you wouldn't want to look at it


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## dwalstad (Apr 14, 2006)

The trouble is you might smother the critters in the sludge and turn it anaerobic. They would release toxins, plus you've not remove any nutrients from the system. Better to remove top layer of gravel with attached sludge and replace with clean gravel.


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## HomeroThompson (Mar 15, 2020)

Thank you all for your comments. I was able to remove quite a bit of the sludge. I also added _a lot _of plants, the idea being to hide as much of the remaining sludge (and I agree that the tank was underplanted). Here's how it looks now:










Foeground:

_Helanthium tenellus
Staurogyne repens_

Midground:

Some kind of crypt (C. wendtii maybe?)
_Sagittaria subulata_

Background:

Pearlweed (I think, the store guy wasn't sure either)
_Rotala rotundifolia
Bacopa caroliniana
Echinodorus tenellum _

There's also some spiky moss and _Hydrocotyle tripartita _in the glass cups. I know the Hydrocotyle is a more demanding plant, but I'm hoping it makes it (although it wasn't doing to great when I got it). I'm trying to grow some of it emersed in a cup with dirt, so hopefully that gives me a steady supply to keep trying to grow it submersed.

I got the Bacopa online and they didn't arrive in the best condition; it's a very pale shade of green, almost grayish. No signs of new growth yet (it's only been three days since I planted it). With some luck, it bounces back, although it has a terrible aspect.



dwalstad said:


> The sludge is just microorganisms happily growing in a tank full of nutrients from the decaying plant matter. I'm guessing that bacteria are stuck to the gravel particles (i.e., Eco-complete?) with their sticky biofilms. So it's going to be virtually impossible to remove the sludge without sucking up the gravel.
> 
> The fact that the fish are alive and the dirt doesn't smell suggests that the tank is not a lost cause. I would add more plants to replace those that were lost. (Tank looks "underplanted" to me.) Then, I would add a major clean-up brigade (shrimp, snails, algae-eating fish, etc). A couple Chinese Algae Eaters might clean up that gravel in a couple days? You'll have to experiment with what works best. It may take awhile to get rid of the sludge, but it is not impossible.
> 
> Keep us posted!


The gravel is indeed Eco-complete. For reasons that are still not clear to me, it was cheaper than regular gravel (unless I bought a ridiculous amount) where I'm at. 

I hadn't thought about Chinese Algae Eaters, but I wouldn't have anywhere to put them long term, nor do I know anyone who can lend me some (plus I imagine this would be rather stressful to the fish). I had an amano shrimp there for a couple of days. Thanks again!


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## dwalstad (Apr 14, 2006)

It looks like a new tank! MUCH better. 

Yes, I admit that the Chinese Algae Eater would be overkill. They get really big and nasty--suck the slime coat off of bigger fish. 

It looks like you've solved the sludge problem. Keep us posted on this tank's progress.


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## HomeroThompson (Mar 15, 2020)

Thought I would provide an update:

The _Baccopa caroliniana _did not make it and melted away. Every other plant seems to be doing well, the Rotala in particular has taken off. I added some _Limnophila sessiliflora _to fill the space left by the Baccopa, as well as some unknown red plant that the eBay seller threw in (can anyone ID it?). Hopefully, these plants make it.

The tank currently looks like this:











Thanks again for the help!


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## mistergreen (Mar 3, 2007)

I planted some Baccopa caroliniana cuttings in my pond and they're taking off. I think they're perennials so they should come back after winter.


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## dwalstad (Apr 14, 2006)

Wow! What a transformation. Just proves that even the most dismal tank situation can be rescued by time and more plants. 
Red stem plant could be _Alternanthera reineckii _"Red." The bigger fish looks like a female Killifish? (I just bought some Gardneri.)
Actually, in comparing prices, you are right than Eco-complete is a lot cheaper than aquarium gravel. What is your opinion of using Eco-complete as a topping for soil?
Again, kudos for your successful "tank make-over" and thanks for posting the results.


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## HomeroThompson (Mar 15, 2020)

dwalstad said:


> Wow! What a transformation. Just proves that even the most dismal tank situation can be rescued by time and more plants.
> Red stem plant could be _Alternanthera reineckii _"Red." The bigger fish looks like a female Killifish? (I just bought some Gardneri.)
> Actually, in comparing prices, you are right than Eco-complete is a lot cheaper than aquarium gravel. What is your opinion of using Eco-complete as a topping for soil?
> Again, kudos for your successful "tank make-over" and thanks for posting the results.


Yes the bigger fish is an adult female _Fundulopanchax gardneri. _The smaller one is a juvenile of the same species, I think it's a female, but there's a large black mark on the head that gives me some pause. My male sadly passed away a few months ago, I'm trying to find a single male for sale (I have a third female that is currently separated until she puts on some more weight, the largest one was nipping at her). They are beautiful fish. I'm sure you know this, but you want a tight fitting lid, as they're very prone to jumping, specially as you're just about to feed them. The large female did jump out once while I opened the lid and was about to pop in the food. Thankfully, she seemed to emerge unscathed.

I've been liking Eco Complete for the most part. There's no need to rinse, which is relevant for me since I don't have a ton of space. I find the black tone aesthetically pleasing, but of course that's very subjective. It is quite light, so if, say, frogbit roots grow down to the substrate, you can expect to pull up a decent bit of Eco Complete with the plants as you remove them. This was partially the reason for switching to Salvinia sp as the floaters of choice. It can also be a bit challenging to plant in, specially with smaller plants, because the grain size is rather coarse and some plants might float up. I've had to reinsert some plants into the substrate a few times while getting started. Once the roots take hold, it's much stable. 

Thanks again for your kind words


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