Weird smell in aquarium after gravel vac

[Jesse L]

Hi, i have a 40 breeder with a 2-3 inch sand substrate. Last night I did  gravel vac in a few places I normally don’t do. I believe I released hydrogen sulfide because now that water stinks really bad.  I placed a bag of activated carbon, two air stones and increased filter flow. No loses yet but wanted to see if there’s anything else I should be doing to prevent any. Would a large water change help out? 
 

Thanks

[Fish Folk]

Sounds like you’re on this right. Personally, I’d not do anything drastic. Stick to normal water change schedule.

I think H2S builds up, especially under densely packed sand, due to anaerobic bacteria.

[Sarina]

Rotten egg smell is an indicator of hydrogen sulfide, but what I would be more concerned about is the potential for an ammonia spike due to a mass die off of bacteria. Bacteria that thrives in an anaerobic or anoxic environment will die when they are exposed to too much oxygen at once, which does have the potential to cause bad odor.

I think the most likely scenario is that you just released some gnarly-smelling phenols into the water, which the carbon will take care of. Phenols are naturally produced by decaying matter, especially plant matter, and are the primary reason that an aquarium will smell bad. Occasionally this will happen to one of my blackwater tanks if I uproot a plant because of the botanicals that decay naturally and fall into the substrate. 

[Jesse L]

On 7/14/2023 at 2:02 PM, Nirvanaquatics said:

Rotten egg smell is an indicator of hydrogen sulfide, but what I would be more concerned about is the potential for an ammonia spike due to a mass die off of bacteria. Bacteria that thrives in an anaerobic or anoxic environment will die when they are exposed to too much oxygen at once, which does have the potential to cause bad odor.

I think the most likely scenario is that you just released some gnarly-smelling phenols into the water, which the carbon will take care of. Phenols are naturally produced by decaying matter, especially plant matter, and are the primary reason that an aquarium will smell bad. Occasionally this will happen to one of my blackwater tanks if I uproot a plant because of the botanicals that decay naturally and fall into the substrate. 

@NirvanaquaticsWould adding live bacteria fritz turbo start be a good idea? Also how long does the smell last from your experience?

[Sarina]

@Jesse L Turbo Start may be unnecessary, just keep an eye on water parameters and do a water change if you see anything alarming. You can also treat with a dechlorinator that detoxifies ammonia. The smell usually dissipates within a day or two if I throw some activated carbon in. This is actually one of the few instances where I will use activated carbon, it is really good at absorbing gross smells.