Aquarium Smells! How to get rid of smell?

[Carolyn Underwood]

One time it got very stinky around my tank and it took me days to figure out what it was...sour milk smell. I got a glass and took some water out, but it wasn't the water. Finally, I found something on the inside of the tank lid that smelled horrible...was wet fish food. I am only 5' tall and the top of my tank is about at the 5'4" level. The fishfood was caked on the inner ledge of the little lift door where you put food in for the fishies. Guess it got wet and spoiled.

 

[RedLoredAmazon]

I had cyano growing on the lid of my aquarium and that made my house smell awful! I couldn't figure out where the bad smell was coming from till I was doing a water change with my kids around. They told me that the tank had a "green ceiling" (the lid had cyano growing on it). I cleaned that off and poof the smell was gone!

 

[MaximumRide14]

One time it got very stinky around my tank and it took me days to figure out what it was...sour milk smell. I got a glass and took some water out, but it wasn't the water. Finally, I found something on the inside of the tank lid that smelled horrible...was wet fish food. I am only 5' tall and the top of my tank is about at the 5'4" level. The fishfood was caked on the inner ledge of the little lift door where you put food in for the fishies. Guess it got wet and spoiled.

I had cyano growing on the lid of my aquarium and that made my house smell awful! I couldn't figure out where the bad smell was coming from till I was doing a water change with my kids around. They told me that the tank had a "green ceiling" (the lid had cyano growing on it). I cleaned that off and poof the smell was gone!

I'm going to go check for all of that right now!

You said you smelled the carpet?
Got a sister?
Make her get down there and smell that badboy! Lol
Sibling experiments are the best experiments.
Carpet cleaning is expensive here.. I wouldn't want to waste a bucket of cash on carpet cleaning if the carpet and walls actually do smell fine.

Yeah, it's expensive here too, which I why I feel kind of bad. I could ask my brothers (only girl here with 3 brothers haha) but they aren't willing participants haha. My mom smelled it and she wasn't able to distinguish whether it was the source.

EDIT: No cyanobacteria growing on the lids, though I do have some growing in one of the tanks. I also got rid of all the grime from calcium buildup and leftover food (which was turning green.. ugh) from the tank. There wasn't too much though, but I got rid of it so hopfully that helps.

 

[Robert Fletcher]

The other thing to consider is Blue-Green Algae (Cyanobacteria). It is like a dark green to black slime on anything. and it stinks. I doubt ammonia as when it gets to that level and it is gassing off the fish will be dead.

 

[Ronniethewitch]

once you find the culprit, can I share a trick I found quite by accident? I was treating a damaged fin with both pimafix and melafix (healed beautifully) and I loved the smell - I began adding a spoonful of each into only one of four buckets I do every waterchange for preventative reasons and found that the fish LOVE swimming under only THAT bucket when I refill, and it also makes the room smell lovely...just a thought.

 

[MaximumRide14]

The other thing to consider is Blue-Green Algae (Cyanobacteria). It is like a dark green to black slime on anything. and it stinks. I doubt ammonia as when it gets to that level and it is gassing off the fish will be dead.

I do have cyano in one tank, but I’ve been controlling it by cleaning it every week. I’ve also added some duckweed to reduce the light and taped some construction paper to the side of the glass where sunlight was coming through.

once you find the culprit, can I share a trick I found quite by accident? I was treating a damaged fin with both pimafix and melafix (healed beautifully) and I loved the smell - I began adding a spoonful of each into only one of four buckets I do every waterchange for preventative reasons and found that the fish LOVE swimming under only THAT bucket when I refill, and it also makes the room smell lovely...just a thought.

Nice! Maybe I can use that in the future.

The smell has gone down a lot. I’m not sure if it was the gravel of something else I’d done, but I don’t really smell it anymore. My guess is that it was the carpet, but over time the stench wore off. I don’t know what else it could’ve been.

 

[sipec]

If it picks up again, I think carbon absorbs smells but I would have to check

 

[Suzanne2]

Your description of a sour milk smell made me immediately think of dead snails.
It is amazing how bad a small snail can smell, and how far the smell can spread!
Sometimes my snails crawl out of the tank during water changes because they were near the surface when the water level went down and they end up on the lip of the aquarium where little bits of water have collected. I always have to be careful not to put the lid down and crush them accidentally .
Maybe one of your snails ended up where it got out of the tank and died?

 

[Chooklady]

I had a peculiar foul smell after a few weeks with a large tank. It was really upsetting me because it looked fine and I was water changing huge amounts to try to get rid of it. LFS said it was an algae, they had this problem recently. I put algae killer in, luckily only half the amount. My fish nearly shut down. It was quite frightening. They are cichlids. They recovered after about six hours. I can’t remember if I water changed again, I probably did, in panic. Anyway that evil stuff got rid of the smell so I would say the LFS was right. My fish tank only ever has a normal rich earthy smell at most and not that alarming foul smell. Honestly I was battling ten days until I put the algae killer in but the dose nearly killed my fish at half dose.

QUOTE="MaximumRide14, post: 3880734, member: 89707"]Wow, I've been having lots of questions these days. So I have 5 tanks in my bedroom, 3 ten gallons and two 5.5 gallons. Yesterday I did water changes on 4 tanks, and I do the last one today. Last night I began to notice a really disgusting smell, kind of like sour milk. This morning it was worse, my parents and siblings could smell it too. I've used air freshener and opened up my windows the whole day, but it's still prominent. I think it has something to do with the water changes because the smell came after them, but I'm still not completely sure? I didn't get that much tank water on the carpet, and even then the smell doesn't last that long. Any idea on what it can be?
I do water changes every other week with the substrate siphon.[/QUOTE]

 

[nolongeractiveonthissite]

Hello!
My tank smells fishy for a few hours everyday, in the afternoon.
And the other times it has no odor at all.
I was wondering why? And what can I do about it?

 

[FishGirl38]

I'm not exactly sure why it would smell at only a specific time during the day, usually if there is an odor it lasts.

and well, there are organic compounds in the water that're making it smell. Do you use carbon in your filter at all?

 

[Guppygirl88]

as in dead fishy? or just fishy fishy ? If all your numbers are right and your doing your water changes a little fishy smell is to be expected. It could be air circulation in the room .Your up moving around stirring up the air in the room .It's good though that your aware of the way it smells, sometimes scent is the first indicator that something could be off in your tank.

 

[nolongeractiveonthissite]

and well, there are organic compounds in the water that're making it smell. Do you use carbon in your filter at all?

But, isn't it supposed to smell okay unless there's something wrong with it?
I've never used carbon! Maybe I should?? But then I wouldn't know if something goes bad in my tank..?

as in dead fishy? or just fishy fishy ? If all your numbers are right and your doing your water changes a little fishy smell is to be expected. It could be air circulation in the room .Your up moving around stirring up the air in the room .It's good though that your aware of the way it smells, sometimes scent is the first indicator that something could be off in your tank.

Well, it's not a pleasant fishy smell! My tank used to smell nice like wet soil a month ago, I don't know why it smells bad now..

 

[MomeWrath]

If it smells bad, like anything other than say, wet earth or puddle, then I would bet there is something going on. Can you tell us more about your tank? Size, stock, filtration, is it planted, maintenance schedule, water changes, etc
There is an old saying, "The solution to pollution is dilution." i.e. when in doubt, do a water change. That would be my first step anyway.

 

[FishGirl38]

It won't smell pleasant all the time, when its newer it might but as it ages, it's going to get a little more 'organic' smelling. Carbon is used for binding with and pulling odors, discolorations, and chemicals (like medications or sprays or anything that accidentally gets into the aquarium) out of the aquarium. If you were to add carbon to the filter, I bet the smell would go away in the next 4 days. Its likely a mixture of all the organic waste compounds that've built up in your tank, like nitrates and phosphates.

I once had an slime algae issues caused by high phosphate levels. My tank smelled like a bog...erm, it had a very distinct plant like algae smell. Very strong too. Just check and make sure there aren't any dead fish or fungI growing left over food in the tank, if not, then some carbon would do the trick and it's probably nothing to worry about. If the tank starts smelling AND your using carbon, that's a cause for concern. (I was using carbon with the above, bog smelling example)

With carbon though, there are pros and cons, the pros are above, the cons are that carbon has been said to leach phosphate into the aquarium in small amounts. Also, you'll have to change it on a monthly basis, if carbon is left in the aquarium after a months time, it could start leaching everything that it once pulled out of the aquarium, back into the aquarium. Otherwise its decent media to have on hand.

 

[Guppygirl88]

But, isn't it supposed to smell okay unless there's something wrong with it?
I've never used carbon! Maybe I should?? But then I wouldn't know if something goes bad in my tank..?


Well, it's not a pleasant fishy smell! My tank used to smell nice like wet soil a month ago, I don't know why it smells bad now..

Have you tested your water? High nitrites and ammonia can give your tank a funky pondy smell(not all ammo. smells like something died) Have you changed fish food?or fed live, little uneaten fish parts can create an aroma Try a water change or more frequent water changes but definitely start using carbon it doesn't do anything to help smells it's just another layer of media to grow good bacteria on to keep your water clean

 

[nolongeractiveonthissite]

If it smells bad, like anything other than say, wet earth or puddle, then I would bet there is something going on. Can you tell us more about your tank? Size, stock, filtration, is it planted, maintenance schedule, water changes, etc
There is an old saying, "The solution to pollution is dilution." i.e. when in doubt, do a water change. That would be my first step anyway.

I first worried that something might be wrong when my tank smelled less than one day after water change!
My tank is 40 gallon, it has Anubias and Java fern and moss, and Angelfish and Gourami and guppy and snails.
I change 30% water every week.

It won't smell pleasant all the time, when its newer it might but as it ages, it's going to get a little more 'organic' smelling. Carbon is used for binding with and pulling odors, discolorations, and chemicals (like medications or sprays or anything that accidentally gets into the aquarium) out of the aquarium. If you were to add carbon to the filter, I bet the smell would go away in the next 4 days. Its likely a mixture of all the organic waste compounds that've built up in your tank, like nitrates and phosphates.

I once had an slime algae issues caused by high phosphate levels. My tank smelled like a bog...erm, it had a very distinct plant like algae smell. Very strong too. Just check and make sure there aren't any dead fish or fungI growing left over food in the tank, if not, then some carbon would do the trick and it's probably nothing to worry about. If the tank starts smelling AND your using carbon, that's a cause for concern. (I was using carbon with the above, bog smelling example)

With carbon though, there are pros and cons, the pros are above, the cons are that carbon has been said to leach phosphate into the aquarium in small amounts. Also, you'll have to change it on a monthly basis, if carbon is left in the aquarium after a months time, it could start leaching everything that it once pulled out of the aquarium, back into the aquarium. Otherwise its decent media to have on hand.

Oh interesting. OK I'm definitely gonna add carbons then. I had no idea about phosphates, like it's the first time I'm learning this! Thank you, I hope nothing is seriously wrong with my tank.

 

[MomeWrath]

I first worried that something might be wrong when my tank smelled less than one day after water change!
My tank is 40 gallon, it has Anubias and Java fern and moss, and Angelfish and Gourami and guppy and snails.
I change 30% water every week.

Sounds all good to me. That's all I've got, sorry My tanks all smell like lake water, but I love it. Smells like home.

 

[nolongeractiveonthissite]

Have you tested your water? High nitrites and ammonia can give your tank a funky pondy smell(not all ammo. smells like something died) Have you changed fish food?or fed live, little uneaten fish parts can create an aroma Try a water change or more frequent water changes but definitely start using carbon it doesn't do anything to help smells it's just another layer of media to grow good bacteria on to keep your water clean

I did test my water, but there wasn't anything wrong, my nitrates are less than ever!
Right, I'm gonna do more water changes then, maybe twice a week? And adding carbon right away. Thank you!

Sounds all good to me. That's all I've got, sorry My tanks all smell like lake water, but I love it. Smells like home.

I know! My tank smelled so nice until a couple of weeks ago, everyone loved it! I hope more water changes and carbons for a while can fix it..
Also some leaves of my Java fern are dying, but I don't know if that can be the cause of the odor?

 

[kallililly1973]

You should do a 50-60% WC once a week as opposed to 30% also if you use carbon you will need to replace it every 4-6 weeks. Also if you have any dying plant leaves cut them or pull them right out it will help with your water quality as well as helping your plant grow instead of struggling to try to repair an already too far gone leaf. Good luck! Do you have pics so we can se it
Edit: forgot to ask at the time you smell the water is there a window sending sun into your house and on the tank possibly?

 

[skar]

I did test my water, but there wasn't anything wrong, my nitrates are less than ever!
Right, I'm gonna do more water changes then, maybe twice a week? And adding carbon right away. Thank you!


I know! My tank smelled so nice until a couple of weeks ago, everyone loved it! I hope more water changes and carbons for a while can fix it..
Also some leaves of my Java fern are dying, but I don't know if that can be the cause of the odor?

Have you had the tank setup for awhile ? A year or so ?
The issue could be Old tank syndrome.

If that is the case a deep clean under rocks and ornament vac can help.
And I suggest purigen over carbon for your water organics removal.
Does a better job and lasts longer.

You also cooks l could consider poly fill fir your filter. Same idea polishes organics for a clean look .

 

[nolongeractiveonthissite]

You should do a 50-60% WC once a week as opposed to 30% also if you use carbon you will need to replace it every 4-6 weeks. Also if you have any dying plant leaves cut them or pull them right out it will help with your water quality as well as helping your plant grow instead of struggling to try to repair an already too far gone leaf. Good luck! Do you have pics so we can se it
Edit: forgot to ask at the time you smell the water is there a window sending sun into your house and on the tank possibly?

Thank you!
But the dying leaves have little baby java ferns growing on them so I wanted to let them grow bigger???
There's no window, BUT, the smell kinda starts around the time when I turn on the aquarium light. Could it be related??
(And I'll take a pic tomorrow!)

Have you had the tank setup for awhile ? A year or so ?
The issue could be Old tank syndrome.

If that is the case a deep clean under rocks and ornament vac can help.
And I suggest purigen over carbon for your water organics removal.
Does a better job and lasts longer.

You also cooks l could consider poly fill fir your filter. Same idea polishes organics for a clean look .

Thank you, I hadn't heard of purigen and stuff! I'll look into it. And no my tank has been up only for a couple of months.

 

[nolongeractiveonthissite]

By the way, my tank still stinks for a couple of hours, at around 1pm when I turn on the lights, and I've been using carbon for a month but hasn't helped.

 

[CheshireKat]

Do the lights heat up or add heat? Heat usually hastens decay and makes things smell worse. Ever had a full garbage can in a hot, stuffy house? Terrible.

 

[nolongeractiveonthissite]

Do the lights heat up or add heat? Heat usually hastens decay and makes things smell worse. Ever had a full garbage can in a hot, stuffy house? Terrible.

No, it's LED and like a meter above the tank. Though I know what you mean by the garbage thing! It is terrible. But yeah, I do monitor the temperature and it's stable at 79 or so.

 

[mattgirl]

Since you notice the smell after turning on the light have you checked the underside of the light to see if maybe some type of mold has taken up residence up there?

 

[CheshireKat]

Since you notice the smell after turning on the light have you checked the underside of the light to see if maybe some type of mold has taken up residence up there?

That's what I was wondering and was going to ask next. Seems like some thing's gotta be going on with the lights...

 

[nolongeractiveonthissite]

Since you notice the smell after turning on the light have you checked the underside of the light to see if maybe some type of mold has taken up residence up there?

OK I just checked and found nothing. All seems okay. I don't even have any visible algae.

 

[mattgirl]

OK I just checked and found nothing. All seems okay. I don't even have any visible algae.

Looks like we can check that off the list of possible reasons then. I know my tanks have their own unique odor. Not really unpleasant but there nonetheless.

It was kinda unpleasant way back during the time I had an infestations of pest snails. I got the snail population down to manageable levels and ran carbon in my filters for a short time and it removed the not so pleasant odor.

Do you by any chance have snails?

 

[nolongeractiveonthissite]

Looks like we can check that off the list of possible reasons then. I know my tanks have their own unique odor. Not really unpleasant but there nonetheless.

It was kinda unpleasant way back during the time I had an infestations of pest snails. I got the snail population down to manageable levels and ran carbon in my filters for a short time and it removed the not so pleasant odor.

Do you by any chance have snails?

Yeah, I have ramshorns and mts. They're causing the smell?? (ﾉﾟ0ﾟ)ﾉ
But did your tank also smell for only an hour a day?

 

[mattgirl]

Yeah, I have ramshorns and mts. They're causing the smell?? (ﾉﾟ0ﾟ)ﾉ
But did your tank also smell for only an hour a day?

The snails is what I blamed mine on. They may have had nothing to do with it but once I brought the number of snails down and ran carbon for a short time the odor was gone.

No, the odor was pretty much there all the time.

 

[nolongeractiveonthissite]

The snails is what I blamed mine on. They may have had nothing to do with it but once I brought the number of snails down and ran carbon for a short time the odor was gone.

No, the odor was pretty much there all the time.

Then it's still a mystery why it only stinks for a short time, and I'm using carbon in my filter all the time but still nothing!
But I'm gonna get rid of snails and see if it helps (they're eating my plants anyway!) Did you use chemicals to get rid of them or maybe with assassin snails?

 

[mattgirl]

Then it's still a mystery why it only stinks for a short time, and I'm using carbon in my filter all the time but still nothing!
But I'm gonna get rid of snails and see if it helps (they're eating my plants anyway!) Did you use chemicals to get rid of them or maybe with assassin snails?

Assassin snails

 

[CindyVBPets]

Do you have wood in there? I bought a big piece on a slab from my local store's live tank when I was cycling a new tank and that thing ended up smelling up my tank and I found it had like a slime coating. I saw guys on youTube showing how to "clean it" but I just took it out permanently.

IDK about your light but I returned a Nicrew LED because it was heating up my 5 & 10 gallon tanks and Versa top for real. It sat very close to the glass. I just went back to old school florescent bulbs and a full lid.

Does it smell if you DON'T put the light on?

 

[nolongeractiveonthissite]

Do you have wood in there? I bought a big piece on a slab from my local store's live tank when I was cycling a new tank and that thing ended up smelling up my tank and I found it had like a slime coating. I saw guys on youTube showing how to "clean it" but I just took it out permanently.

IDK about your light but I returned a Nicrew LED because it was heating up my 5 & 10 gallon tanks and Versa top for real. It sat very close to the glass. I just went back to old school florescent bulbs and a full lid.

Does it smell if you DON'T put the light on?

I do have driftwood. Maybe tomorrow I can get it out and see if the tank still stinks or it was the driftwood.

But I don't really think the lamp is heating, cause it's like 2 feet above the aquarium.

Also, I haven't tested without turning on the lights. I could test it, but won't it be bad for plants?

 

[CindyVBPets]

I do have driftwood. Maybe tomorrow I can get it out and see if the tank still stinks or it was the driftwood.

But I don't really think the lamp is heating, cause it's like 2 feet above the aquarium.

Also, I haven't tested without turning on the lights. I could test it, but won't it be bad for plants?

I don't think it'll hurt anything having no light for one day. I'd try removing snails first.

 

[nolongeractiveonthissite]

So in case anyone was wondering, I removed the driftwood but my tank still smelled.
I ended up removing the whole gravel and changing substrate, and I got rid of all the snails. Now my tank doesn't smell anymore. At least not yet!
So the problem might have been the snails or something else about the gravel.

 

[jdhef]

One other source of a bad small that a lot of people don't think of is if fish food gets left on the rI'm of the tank or on the cross brace, you'll start getting a rather unpleasant odor.

 

[nolongeractiveonthissite]

One other source of a bad small that a lot of people don't think of is if fish food gets left on the rI'm of the tank or on the cross brace, you'll start getting a rather unpleasant odor.

Makes sense, but it still beats me why it only smelled for a couple of hours a day, and was perfectly fine the other times.

 

[Momgoose56]

Makes sense, but it still beats me why it only smelled for a couple of hours a day, and was perfectly fine the other times.

Okay, if the smell only happens when you turn the lights on, it's reasonable to assume that the odor is being caused by something in the light itself-or something the lights are heating up in the tank. Do your lights sit directly on top of a glass hood? Is there any organic material or water condensate inside the hood the lights could be heating up when they're turned on? Did you check carefully inside the light housing to make sure some big juicy bug didn't crawl in there and keeps getting broiled every time you turn the lights on? Did you check your light cord to make sure it isn't heating up and creating the smell?

 

[nolongeractiveonthissite]

Okay, if the smell only happens when you turn the lights on, it's reasonable to assume that the odor is being caused by something in the light itself-or something the lights are heating up in the tank. Do your lights sit directly on top of a glass hood? Is there any organic material or water condensate inside the hood the lights could be heating up when they're turned on? Did you check carefully inside the light housing to make sure some big juicy bug didn't crawl in there and keeps getting broiled every time you turn the lights on? Did you check your light cord to make sure it isn't heating up and creating the smell?

My lights are regular tubes without hoods or reflectors, and I didn't see anything that would be making the smell. And now that I've changed the substrate and have no snails, there's no smell. I didn't change the lights, so I don't think they were the problem...

 

[Momgoose56]

My lights are regular tubes without hoods or reflectors, and I didn't see anything that would be making the smell. And now that I've changed the substrate and have no snails, there's no smell. I didn't change the lights, so I don't think they were the problem...

K you fixed it! It was probably dead and dying snails.

 

[MileyMorkie]

I've dealt with foul aquariums and the key things you need to know is phosphor. Your fish food, veggies, or filter can be the cause.

Dead snails can raise the ammonia by quite a lot. (we all know how awful ammonia smells) One thing to do is to be cautious of is the amount of phosphor found in peas. If you feed them algae wafers or some kind of tablet put it in a cup of water and let it sit, sometimes those things will be the cause. Clean or replace internal filter media sometimes that can cause the odour to linger. Try aeration pumps in the tank or lifting the lid at the hours the scent comes at. Water changes will do the trick to dilute and eliminate the stench but every single detail counts.
Oh almost forgot to include this; you should wipe down the lid as mould, food and other nasties can accumulate on the lid.

I mostly just burst in here to help didn't stop to read much of anything so if I missed details to the thread, I'm sorry for that.

 

[jdhef]

I'm happy to see the problem was solved

 

[Cdbaby123]

I am cycling a tank with fish, I had no idea about the cycle until after I began.
I am 4 and a half weeks in and it smells... I have done water changes. I have a betta 3 black neon tetras and a neon tetra (the tetras are inherited). I also have 8 miramo moss balls in the tank. 10 gallon tank.
My husband thinks it is coming from the filter. Since I am cycling I have not cleaned the media...
Is this normal?

Ammonia .5
Nitrites .5
Nitrates 10

 

[saltwater60]

Not normal. Toss in some carbon and it will remove the smell. You are likely over feeding or feeding some kind of shrimp.
I had a turtle for years and it never smelled. I was like oh I’ll buy him some freeze dried shrimp as a treat and now his tank smells.

 

[Cdbaby123]

Not normal. Toss in some carbon and it will remove the smell. You are likely over feeding or feeding some kind of shrimp.
I had a turtle for years and it never smelled. I was like oh I’ll buy him some freeze dried shrimp as a treat and now his tank smells.

Only feeding once a day. 2 pellets for betta and a pinch of tetra food for 4 tetras. I think I am under feeding. No shrimp.
Where do I add the carbon? Is it a powder or liquid?

Not normal. Toss in some carbon and it will remove the smell. You are likely over feeding or feeding some kind of shrimp.
I had a turtle for years and it never smelled. I was like oh I’ll buy him some freeze dried shrimp as a treat and now his tank smells.

Ok after some research. Carbon is a filter. I have been told even on this forum do not change or clean media while cycling. So should I change or clean the media at this time. The filter is dirty. I can see that, that is why I asked the question in a separate post a few days ago....
I will have to go back and reread those answers.

 

[A201]

Might have some rotted food on the upper rI'm of the tank or some food particles splashed up underneath the lid. Doesn't take much rotten food residue to start stinking.

 

[Deku-Cory]

Ammonia has a swampy smell to it in aquariums. That might be it.

 

[kallililly1973]

Drop a mesh bag of carbon right in your filter as saltwater60 said. And as A201 also said check around the rI'm for rotting foods