Noticed a very strong smell coming from the aquarium

HI Guys

One of my tanks has been up and running for about 7 months now and has three juvenile fancy goldfish in there (Oranda, Pearlscale and a Black Moor) all around 1 - 2 inches in length minus tail. Yesterday I completed the usually weekly 60 percent water change, exactly the same way that I have always done it and never had a problem.

This morning I noticed a very strong smell coming from the aquarium (it seemed like it was coming from the water and not the filtration system) and I can't put my finger on it. It definitely isn't a pleasant smell. My water parameters are all fine as normal, the filter media was rinsed in tank water and the tank itself is bare bottomed so I know I was able to gravel vac all of the waste off of the bottom.

The only thing I didn't do this time around was to clean the algae off the inside of the tank glass. I have several nerite snails in this tank and I wanted to ensure they have plenty of food sources due to it being autumn and the water temperature cooling down quite rapidly know in the north of England.

Does anyone know if this could be the algae making the tank smell? I'm completely baffled by it but can't for the life of me pin down where it is coming from.

EDIT: I forgot to mention that there are several plants in this tank and also floating Salvinia, not sure if they would contribute to this.

Many thanks

 

Do you have an airstone? I once had this problem, turns out it came from the airstone. I washed it and that was that.

 

HI Kurimu.Neko

I don't have airstones in my tanks but I run two sponge filers alongside my regular filter which creates a lot of aeration in the water. I have a sponge over the power head of the regular filter also to create more surface area for BB. I am currently running a heater to maintain a temperature of 20 degrees celcius to ensure that there isn't so many temp fluctuations due to the really cold nights we are having. I believe this autumn has been one of the coldest in the last 30 years in my area.

Do you think the heater could be contributing to the smell if the water is being warmed? The heater is relatively new as over the summer the tank maintained a stable temperature so this wasn't required.

I know it is not always necessary to run a heater with goldfish, however with them being juveniles I didn't want the water temperature fluctuations to upset them.

 

How often do you wash/squeeze out your sponge filters?

 

Try adding some activated carbon into your filter to remove the odor.

 

HI Kurimu.Neko

I don't have airstones in my tanks but I run two sponge filers alongside my regular filter which creates a lot of aeration in the water. I have a sponge over the power head of the regular filter also to create more surface area for BB. I am currently running a heater to maintain a temperature of 20 degrees celcius to ensure that there isn't so many temp fluctuations due to the really cold nights we are having. I believe this autumn has been one of the coldest in the last 30 years in my area.

Do you think the heater could be contributing to the smell if the water is being warmed? The heater is relatively new as over the summer the tank maintained a stable temperature so this wasn't required.

I know it is not always necessary to run a heater with goldfish, however with them being juveniles I didn't want the water temperature fluctuations to upset them.

I mean if when you added the heater the smell instantly came, it is possible that the smell came from it, but if you want to keep the heater, I would also recommend adding activated carbon.

 

I normally squeeze out my sponge filters probably once every two weeks during a water change - do you think this may be a contributing factor?

Thank you for your responses everyone, I have some activated carbon already so I will give this a try and what results I get with it. Hopefully this will help!

 

I normally squeeze out my sponge filters probably once every two weeks during a water change - do you think this may be a contributing factor?

Thank you for your responses everyone, I have some activated carbon already so I will give this a try and what results I get with it. Hopefully this will help!

Not at all, every two weeks is fine. I was just checking to see you did it so that gunk wasn't building on the sponges. They need to be squeezed out in aquarium water at least once a month minimum, so that's fine!

Run some carbon as others have said and it should deal with the smell. I just wanted to check if there was a cause to prevent it happening again. I know mine smells a little sometimes when algae builds up, but my tank is not very old so I'm dealing with the diatom/algae issue that's more common in recently cycled tanks

 

Clean the edges of the tank and make sure there isn't fish food rotting there

 

Check all nooks and crannies like under the hood. Move things around, if you haven't, to be sure no gunk build up somewhere.

I know this seems weird and it is probably is not the case, but outlets and other electrical devices can put out a funky smell when they start to burn. So as a precaution I would suggest carefully checking to be sure it isn't an electrical issue.

I once worked in an office where unbeknownst to us, wires in the wall were burning inside the wall. It didnt smell like you would think that would, we kept blaming it on a nearby potted plant...

 

Thank you all for your help with this.

As suggested I have been running carbon in my filter which helped reduced the smell but didn't remove it completely.

I was doing my usual maintenance yesterday and think I discovered the problem. I had a fair bit of Christmas Moss in my aquarium that seemed to be doing okay. However, now that the winter is coming in and daylight is short and limited I think the moss began to die off in my tank due to insufficient lighting. I have other plants that are doing okay but they are not light demanding.

I picked some of the moss out of the water while cleaning and they smell of it was horrendous, so I immediately removed it all. After about and hour the smell had completely disappeared from the tank so I can only imagine it was the decaying plants. I immediately changed 80% of the water after I realised and I think everything is back on track now!

Thank you for all of your suggestions with this!