# Wood is rotting in my tank?



## JJ09 (Sep 11, 2014)

Since my betta fish is in hospital tank I thought I'd do a little rescape now, so things can settle again before he goes back in. I lifted up the main piece of driftwood that's in his 10gal tank and there was a bad smell like rotten eggs, some bubbles came up, and the substrate (fine gravel/coarse sand and STS) is very black underneath. I found it alarming. I put the driftwood in a bucket of tank water and could rub off outer layer that had turned black, plus some of the normal-colored brown wood underneath it is really soft. I didn't rub loose stuff off the whole thing because have anubias, buces and moss tied on top. 

This is wood I bought at the pet store. It was in the reptile section but said on the label "for aquarium and terrarium use". At the time (2+ years ago) I soaked and boiled it until tannins didn't come out- cut it in half becuase it was so big, the other half is in my 38 gal. That one has no issues- it has not gone soft and when I move it, there aren't black patches underneath or any bad smell. Both tanks have malaysian trumpet snails. The betta's tank is only two degrees warmer. Is that enough to make such a difference?

I am not sure if I should remove the plants, scrape all the soft stuff off the wood, and return it to the tank. Or remove the plants and put them on a new piece of driftwood? (my one piece of mopani wood has never caused any problems like this).

Advice? thanks

Bump: Also not sure if the rottenness caused this population of limpets in my betta tank, do they feed on decaying wood?


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## Nordic (Nov 11, 2003)

Wood has a finite lifespan in the tank, some last longer than others... 
I would take it out and get a new piece, unless you have the kind of money needed for fake foam wood pieces.


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## PlantedRich (Jul 21, 2010)

Wood is organic and does do the natural things. Sometimes that is rot. But then how to deal with the question is open and depends on several other things. 
Is the "look" of the wood a problem? Not much to do other than clean it or change it. Depending on your view, it may be better to change your view of what it should look like. 
Then there is the worry factor. We worry that it may be doing some kind of harm. All things organic become waste (ammonia, nitrite and then nitrate?) so the question may be how much problem is the resulting nitrate. Overwhelming the filter or the cleaning crew so that removing potential nitrate producers would help? 
For my personal outlook, natural is fine with me and I know some wood will rot quicker than others. But if it doesn't become a problem and fall apart so that junk is floating around, I tend to leave it and not worry the issue. With all the water changing I do, the added amount due to the wood is not something that I'm willing to go to much trouble to remove and change wood to reduce. 
Trapped gases, etc. to worry about do not seem real to me and I have never seen any cause for alarm on my tanks. Someway the idea that very much gas can be held down to collect under the things I use, just doesn't seem right. If I had a sub that created a crust of some sort, I might buy into the idea but getting sand, gravel, etc. to pack that tight seems too much. One thing we do know about any gas is that it will go to the top and leave pretty easy so collecting enough to harm the fish seems out to me.


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## Waterski (May 4, 2015)

I had a piece of driftwood that became kinda soft after 4 years or so. It was black breaking apart when being moved around. I dont think it was smelly though


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## Olskule (Jan 28, 2010)

The reason one piece of wood is rotting while a different part of the same exact piece of wood is not rotting could be due to being different parts of the tree/branch/etc., in that one piece (the still solid part) may be from "heartwood" (the inner, more dense portion of a trunk/branch/etc.), while the other may be the "sapwood" (the outer, less dense portion). Heartwood is naturally more resistant to rotting due to its higher density. That is why you will often see a rotted log that has quickly decayed down to the grainy, knotty, and usually more interesting and attractive piece of heartwood that may seem to stop decaying for years. As to what effect this has or had on your aquarium, if the rotting material on the bottom of the wood was left undisturbed, it was in a place that was not exposed to the normal flow of water to begin with, and likely had little influence on the quality of water in circulation. It was only by moving it and disturbing the isolation of the conditions that you noticed the "bad smell" that resulted from the anaerobic activity. Of course, any anaerobic activity is (generally) considered to be "bad", but is usually in such small amounts within our aquariums as to go unnoticed and be inconsequential. If you want to keep the piece of wood, you may want to try gently removing only the softest parts of it and placing it in a position that provides more circulation around the bottom and less area that is isolated from the normally oxygenated water, as in not pressing it down into the substrate, and perhaps moving it regularly to keep noticeable amounts of anaerobic activity from building up. As for any "varmints" that _might_ result from the rot, they, too, would likely be isolated, and _if_ they came out at all, would possibly become a tasty snack for your fish.


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## Albtraum (Dec 27, 2009)

I have some 6+ year old driftwood that has rotted out. Basically falls apart if you rub it, but stays together if you leave it alone. I removed most of the outer part that came off easily, and put it back. Another piece was so water logged I just tossed it.


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## Nordic (Nov 11, 2003)

I suspect having four juvenile bushy nose plecos takes care of any current rotting of wood in my tank.


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## JJ09 (Sep 11, 2014)

Yes, this one was pressed down into the substrate, the piece in the other tank is resting lightly on top. I am not really happy with the looks of it, and it is getting messy with the fine debris that comes off so I'm going to see if I can find another piece similar size to replace. 

The only thing that disappoints me w/that is I had finally got some moss to hold onto the wood and it was beginning to spread.


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## easternlethal (Feb 13, 2016)

Albtraum said:


> I have some 6+ year old driftwood that has rotted out. Basically falls apart if you rub it, but stays together if you leave it alone. I removed most of the outer part that came off easily, and put it back. Another piece was so water logged I just tossed it.


could you tell whether it affected the water in any way? more organics? algae growth?


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## JJ09 (Sep 11, 2014)

Although thinking about it again now in the morning, and after looking at the tank closely w/loop last night, maybe the rotting wood is what has fed my plants. There is a nice buildup of dark mulm under the substrate, at least an inch thick, and I've only ever had one betta and snails in here. I always wondered how the food for a single betta produced enough waste to generate all that mulm. Perhaps it was the wood decaying. There's hasn't been a sudden rise in nitrates, so I'm guessing this has been going on gradually for a long time and I just finally noticed it.


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## PlantedRich (Jul 21, 2010)

Life happens even when we are not paying attention! 
Some of it's good and we like it while some is not. Kind of like wood rotting? It's natural and how we feel about it will vary.


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## Waterski (May 4, 2015)

Can driftwood be taken out of the water, stored for a while and then put back later?


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## PlantedRich (Jul 21, 2010)

Waterski said:


> Can driftwood be taken out of the water, stored for a while and then put back later?


Yes, there is no harm to letting it wait for some time. But then how we store it can also make a difference in what we have when we want to use it later. I find there are two main points to me storing wood for later. One is how much it may float. If I were going to store wood that had finally soaked enough to stay down without weight, I might want to keep it wet. But if I want to put it in the attic or storage for months, I don't worry the weight and I want to let it dry pretty well before I store it. My reason is that damp wood is prone to fungus, mildew, and possible rot, so I want it drier to avoid those. 
So storing it is no problem but how you store it can be different in different situations.


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## Waterski (May 4, 2015)

Thats awesome. I was thinking drying out drift wood would do some damage and may not want to go back into the tank.


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## PlantedRich (Jul 21, 2010)

That is always something that might happen as it dries. There could be some cracks open up as things shrink. but the overall effect is likely to be small enough to not worry. Some depends on type of wood as the grain varies and then there is also the question of what it had been through before. If it is the type wood I use, it's been wet and dried so many times before, that one more cycle doesn't even show. 
When it dries totally like if you store it in a hot and dry place for weeks/months, it will not sink until it gets waterlogged again. that's where I add a few rocks on top. 
Different wood reacts different as far as how long it takes to dry as well as how long it takes to soak up again.


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## AbbeysDad (Apr 13, 2016)

Yep, anything organic that is not living/growing will begin decay when exposed to moisture and microbes. A piece of dry driftwood on a shelf will last forever and a day, but place it out on the ground with moisture (or in the aquarium) and it will begin to decay. As mentioned, the rate of decay is relative to the density of the material and the moisture/microbe/temperature environment. 

Now in some regards, a piece of wood in some state of decay is very natural looking...and after all, with rocks and plants...isn't that what we're trying to achieve?

I see on forums all the time folks obsessing over mulm on the substrate. Some add more filters or power-heads so there are no signs of it. When in fact, mulm is a very natural and healthy part of the tank eco-system. Perhaps some folks don't understand the dynamics of organics in the aquarium, and feel it needs to be removed and replaced with chemicals???

I get a similar feeling when I see somewhat pristine aquascapes that mimic forests (twigs with moss) and meadows and such. To me that looks fake - it just isn't what it typically looks like down under. As someone else mentioned, maybe some folks need to readjust their vision as to what they expect the [planted] aquarium to look like. 

On the other hand, it it's a rotting, stinking mess, maybe it's time for a new piece! <hehe>


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## JJ09 (Sep 11, 2014)

I don't mind the mulm- I know it feeds my plants, I'm glad to see it accumulating up under the substrate. If there's any drifting around just above it, I get that out with the siphon on water change days. It was just when the wood in this tank started emitting sulfrous odor plus big gas bubbles that I thought it had gone too far. And I could scrape well half an inch off all surfaces of it with just my fingernails, when I pulled it out of the tank. I don't know if the wood getting so decayed is what has caused all the little tiny organisms to show up in my tank- the limpets and copepods and springtails... 

Regardless, I've got a nice piece of mopani to replace it with. Boiling on the stove three days now- water is coming off pale tea-colored instead of dark red now. I'm going to scrape down the old wood and see if I can use some in another way, maybe saw it up into rounds to use as bases for subwassertang bushes or something...


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## K1963158 (Aug 15, 2016)

I have Mopani wood in my tank for over 6 years and still going strong. One piece is getting a bit soft but still no problems.

Mopani will leach no matter how long you boil and soak. Putting Seachem Purigen in your filter is an option to deal with the tannin colour.


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## Smooch (May 14, 2016)

AbbeysDad said:


> I see on forums all the time folks obsessing over mulm on the substrate. Some add more filters or power-heads so there are no signs of it. When in fact, mulm is a very natural and healthy part of the tank eco-system. Perhaps some folks don't understand the dynamics of organics in the aquarium, and feel it needs to be removed and replaced with chemicals???


I understand just fine. If I wanted to see fish poop and other tank scum floating around, I'd pass on my tanks and hang around at the local lake which is so disgusting you can't see the bottom of it through the water. 

There are no chemicals in a power head. All they do is move water around. Just ask the people that have had to deal with cyano bacteria because they too believed that layers of mulm as you call it was natural and had some significant meaning in a glass box. Natural bodies of water that have current move the mulm, glass boxes, not so much.


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## JJ09 (Sep 11, 2014)

K1963158 said:


> Mopani will leach no matter how long you boil and soak. Putting Seachem Purigen in your filter is an option to deal with the tannin colour.


Really? I have another piece of mopani in this tank, been there for almost 3 years and it doesn't tan the water at all. This new one is definitely leaching out less tannis since I started boiling it. I don't mind if it leaches a little, but when I first put it in the pot the water came off very dark, almost looked like blood. I don't want my tank water that dark. I think another day or two of boiling and I will be satisfied.


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## K1963158 (Aug 15, 2016)

JJ09 said:


> Really? I have another piece of mopani in this tank, been there for almost 3 years and it doesn't tan the water at all. This new one is definitely leaching out less tannis since I started boiling it. I don't mind if it leaches a little, but when I first put it in the pot the water came off very dark, almost looked like blood. I don't want my tank water that dark. I think another day or two of boiling and I will be satisfied.


No worries, all depends on the wood and size relative to tank water. Mine no longer noticeable leach but did stain the water just a bit for some time. Never really made it "Amazon biotope" dark just stained it a bit. Purigen made my water crystal clear and I still use it. :smile2:


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## Waterski (May 4, 2015)

I personally like somewhat 'dirty' looking tanks with overgrown plants and some algae without a lot of structure. hehe. I am paranoid about not vacuuming the gravel though. I only do it maybe once a month. I also dont prefer free floating organic debris. I guess it is all personal preference. 

I didnt that drift wood decayed in the tank. I thought it was inert. Good to know. I am not sure what kind I have, just got it at the local fish place. Didnt do anything, just dropped it in the tank. It turned the water brown for a few weeks and then it cleared out. I thought my plants started doing much better after that. I guess they like the tannins.

There is no question that water movement is essential. If you have seen the planet earth episode on fresh water, it seems most amazonian planted species barely hold on to the substrate in the rivers. Made sense how they did so well with not a huge source of CO2 in the water column. The high flow clearly breaks the boundary layer on the leaf surface increasing the transfer of nutrients tremendously. I wish there was a way to this without ugly powerheads tho


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## JJ09 (Sep 11, 2014)

Hm, well if lack of water movement speeds decay, that explains part of it. The current is very slight in this tank. I took the old driftwood out and it has been sitting to air dry for several days now. Thought I could scrape off all the soft stuff and salvage some of the core. Doesn't look like it. Still damp and very punky- I can push it with my finger.


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## hubble13 (Sep 1, 2010)

I have driftwood in my tank that been there for about six seven years, give or take and it has started to rot. No bad smell or any thing but any time my corries go near it a cloud of mulm gets launched into the water. I don't mind mulm per-say in fact I think its a interracial part of my tank. But when my filter cant keep up that's when I think its time for a change. 
I have three pieces of driftwood soaking out back now and will be adding extra filtration in the mean time.
After six years its time for a change anyway.
it all depends on what works best for you.


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## Pocho (Dec 3, 2018)

old thread, but this has made me ponder my possible diatom problem or the thought of having diatoms. It may be having a piece of driftwood that's slowly deteriorating where it seems to deposit fine remnants on the substrate near it depending on the placement and of where the water flow takes it. The soot on the substrate looks like a shadow of my rectangle sized driftwood that came with anubias nana petite attached to it. I should have payed more attention to this when I pulled out the piece, rubbing it to remove diatoms and noticing slight brown water that kept rubbing off the piece. Geez, I never thought it could "possibly" lead to this. 
Guess there's only one way to find out and that's removing the wood and replanting the nana petite onto something else. Now that's another thing I have to figure out how I'm gonna get the nana off of the wood and finding something else to attach it to.


Could this wood decay help the cause of unwanted algae growth? of course I could be wrong and I'm still having a diatom problem and the driftwood is somewhat blocking the water flow as to having an outline of it on the substrate.

A newbie with time on my hands trying to rationalize what's happening although it be all unknowing


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## kgbudge (Feb 8, 2019)

A rotten egg smell and black substrate certainly mean hydrogen sulfide in the tank, due to anaerobic conditions in the presence of sulfate. I'd remove the wood, vacuum out the substrate well, and filter/aerate thoroughly before reintroducing any fish. Hydrogen sulfide is highly toxic.

What substrate are you using? Are you adding anything that might build up the sulfate concentration (such as Epsom salts?)


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## Pocho (Dec 3, 2018)

irt kgbudge, no smell clear water may be due to newly inserted activated charcoal and Phosguard trying to control this brownish algae in tank. I used Phosguard thinking silicates as I have used API phosguard test which shows nil or near above that for phosphate
I don't have any rotten egg smell as it is right now, just a possible diatom problem. I've not done any type of salts ever and talking of sulfer type of smell, I use Seachem Prime which smells of it and tried Seachem Excel for a couple of weeks a month ago to no avail.

i have "pink" gravel as substrate, that's what the grandkid wanted. And yeah some months back the water was smelly and there was some very fine particles being released when I disturbed it while vacuuming it. The once very pink gravel has a little brown to in certain areas. LOL

Just too many algae things going on with this tank but my 2 fish seems fine(knocking on wood) its just the diatom, algae that's getting to me. Then I try to vacuum the gravel deeper, cleaning off the diatoms on the glass a couple of small white worm popped out and crawled on glass, GEEZ! one worm looked like a planarian with the shovel head but I did not notice any cocked eyes. Some say not to disturb the substrate but I get tempted and do because I can't stand the brownness it can accumulate.

I usually do 40% water change every 3-4 days for this 5 gallon tank
Maybe got too much time on my hands worrying and wanting things for or of thinking of the tank.


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## JJ09 (Sep 11, 2014)

I think black stuff under your wood is a sign the substrate needs deeper cleaning. 40%wc twice a week for such a small tank seems a bit much- how big are the fish? what kind? perhaps you are overfeeding.

Anubias is pretty easy to remove from driftwood, btw. Just pull firmly and it should come off. You might break a few roots but it will be fine.


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## Pocho (Dec 3, 2018)

irt jj09
it's not of a black substrate under the wood but of the wood being blackish and when you rub it it feels a bit slippery like you could rub off the particles from it. Guess all woods would feel like that, idk.

ah yes, I get to the 40% wc because by the time I vacuum the top and down of about 1/4" of the entire substrate it's just about sucked out 40% of the water column, lol. After 3-4 days the tank starts to look like having a diatom problem, it just gets worse if left alone for a week. I hope I'm not coming down with OCD, lol. I just don't want the algaes to take hold
and yes I'll need to find something to reattach the nana too, sooo many things to think about as I don't have some nice piece of wood/stone laying around. lol But I'll have to remove the wood if wanting to find out if it's the cause of the brownish substrate around it.

I have one neon tetra and one green swordtail. If I didn't have these 2 I think I'd start all over again from scratch. I do add .125ml Thrive with water changes, doing .25ml seems to aid algae growth.


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## JJ09 (Sep 11, 2014)

I see. Maybe you need a smaller siphon? so it doesn't drain as much water? I made a little one out of an airline and old medicine syringe once. Is the tank pretty new? sometimes you just have to wait for diatoms to go away, I know it is a pain. Try to clean as much as you can off each time you do a wc, too- with algae scrubber or old credit card. I use thrive in my 10g, I'm dosing half the reccomended amount too, because I had higher nitrates than I expected and some black algae showing up. It seems better at lower dose for me.


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## Pocho (Dec 3, 2018)

Thanks for the tips!


ps I've read/seen some of your 33 Long, NICE!


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## Pocho (Dec 3, 2018)

JJ09 said:


> I think black stuff under your wood is a sign the substrate needs deeper cleaning. 40%wc twice a week for such a small tank seems a bit much- how big are the fish? what kind? perhaps you are overfeeding.
> 
> Anubias is pretty easy to remove from driftwood, btw. Just pull firmly and it should come off. You might break a few roots but it will be fine.


geez, it's so confusing, I go on the internet and read up on cleaning tanks and some people say not to disturb the substrate as it contains the good bacteria so I never poked the vacuum deep into the substrate for cleaning. After your comment/advice I go off searching again and find some people saying you should vacuum the gravel well and seeing a youtuber deep vacuuming his gravel substrate.

my gravel substrate has brown looking algae buried within itself, on the tank's side walls that's covered by the gravel. As you noted my substrate is Dirty needing a good cleaning.
Maybe the advice against a deep cleaning of the substrate is meant more for a new install, to let the gb get established. I get it now, lol or am I wrong? Geez, live and learn


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## JJ09 (Sep 11, 2014)

Well, I think it depends on the situation. You don't want to clean it too thoroughly, all at once, or you will wipe out much of the good bacteria. You don't want fish waste, mulm to build up a ton either. Or gravel vac where the plants are growing, if they are using that for nutrient. Also if you disturb too much can hit anaerobic pockets which is bad. I keep trumpet snails in my tanks to help stir the substrate. I usually just kind of skim the surface when cleaning, but every now and then use the siphon vac to clean more thoroughly.


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## Pocho (Dec 3, 2018)

I did a good gravel vac and the brown looking algae reappeared on day 3 so today I vacuumed the gravel again, added a little more Phosguard yesterday but still. My Ammonia, nitrite, nitrate, phosphate are 0's.

I caved and detached my anubias nana petite from the driftwood finding, removing the material around the roots were very brown looking like kleenx but of a stronger material in which I cleaned off and wedged the anubias between 2 rocks for now. Hope this was the source of diatoms, idk. I'm guessing here

added newly gotten bacopa too so...


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