# Horrific Odor



## rebelson

As the title states, the odor emitting from my Freshwater Aquarium is rancid. Simply put, it smells like sulfur (rotten eggs). I come home from work late at night and upon entering my house the smell hits me like a ton of bricks. I am quite sure that this odor in larger volumes can be enough to take out a small village :lol:

Ok, enough of the silly comments. I did a 50% water change yesterday and another 25% water change today. The 50% water change was done using my gravel vac and it kinda helped. But for the past few days the water in the tank has been cloudy (white). I am seriously ready to start from scratch because of this new found odor. Now the tank has been cycling for about 2 weeks with only 2 Blue Gouramis. They look as if they are holding up fine, but I am worried that they won't make it through the week. Last thing I want is to have them deal with the issue at hand and 'hope' that they survive. It'll be pure torture if I don't find a solution to this issue. 

I have been testing the ammonia daily for the past few days and it's coming up as 0.25. I have also been testing the nitrites and nitrates and they are somewhat low (can't think of the exact number off the top of my head). For what it's worth I am conditioning the water using Kordon AmQuel Plus and NovAqua Plus. As most of you have already noticed, I am a complete newb to the freshwater aquarium world. By the way, I had posted a thread about excessive air bubbles/foaming on the water surface in my tank. Since the 50% water change the bubbles/foam have gone down considerably. 

I am at my wits end researching a solution to this problem and I am hoping that someone on this great forum can chime in and offer some helpful advice to the issue at hand. 

Thank you!


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## iamntbatman

What sort of substrate do you have? Is it possible something died in your substrate?

What you're smelling is hydrogen sulfide and that's a problem. Anaerobic bacteria (often found in your tank's substrate) metabolize sulfates into this toxic gas. It has a distinct rotten egg smell and is toxic to your fish. If you've got a substrate like sand or even smaller grained gravel that has compacted and there's a lack of water flow in your tank, decaying organic material can provide these bacteria with enough sulfur to produce this gas, which is what you're probably smelling.


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## rebelson

I have freshwater gravel. Nothing has died in my substrate. 


Thank you by the way for clarifying what the issue is. What steps/equipment can you recommend to combat this problem and correct it before it happens again? Thanks.


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## iamntbatman

Increasing water flow and reducing the amount of organic material that could get down into your substrate would be a big help. What sort of filters are you using, and how big is the tank?

I think another problem could be that you have reduced oxygen levels in your tank due to the cloudy white water you're seeing, which is a bacterial bloom. These are pretty common in new tanks, especially ones that are still cycling, as the elevated ammonia levels can result in a bacteria population explosion which results in the cloudiness. These bacteria use up a lot of oxygen. Your gouramis are labyrinth fish that are capable of handling pretty low oxygen levels in the water (they can even breathe air from the surface if need be) but the lack of oxygen may be promoting the growth of the anaerobic bacteria that are causing the nasty smell.

I would continue doing water changes (which you'll be doing anyway because you're cycling with fish). This should help with the bacteria bloom and should put more oxygen into the water. I might also consider temporarily moving the fish to another tank or a large bucket. While they're there, poke around in the substrate (especially in low flow areas and under decor) and see if any gas bubbles come up. If they do, I would thoroughly vacuum that area (deep into the gravel) and I'd probably follow up with a big water change before putting the fish back in the tank.


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## rebelson

Would a powerhead aid in increasing water flow? I have a 46 gallon bow front with a Tetra EX 70 filter. 

I will transfer the fish today and do a thorough water change. Thank you for your help.


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## molliefan09

yes, a power head will help inrease water movement


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## rebelson

Just a small update here....

I did a large water change yesterday (75%) and cleaned the substrate with my gravel vac. Also purchased a Aqua Clear 50 power head and put that in as well. The rotten egg odor went down considerably and everything seemed to be ok. When I woke up today the odor was back again in full force :-(. I did a 25% water change and the odor is still lingering in the tank.

Any suggestions/tips on how to go about getting rid of it? Will daily water changes speed up the process of ridding my tank of this odor? Thanks.


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## iamntbatman

It can't hurt anything. Doing thorough gravel vacs and keeping the substrate from compacting is likely going to give you long-term results. For immediate relief of the odor, you could try using some activated carbon in your filter.


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