Rotten Egg Smell – Hydrogen Sulfide
If your saltwater aquarium smells like rotten eggs (or eggs in general), you’re smelling hydrogen sulfide. In an aquarium environment, hydrogen sulfide is usually caused by organic material (i.e. food particles, feces, dead material) rotting in a place without oxygen.
Usually the only non-oxygenated area in your saltwater aquarium is beneath your substrate. Organic slipped beneath your substrate and is decaying without oxygen. This is basically the nitrogen cycle without the oxygen.
Hydrogen sulfide could occur if you’ve had a power failure and organic material left in the filter has started decaying without oxygen. Make sure you flush out your filter before starting it back up, in this case.
Ways To Address Hydrogen Sulfide Problem
The most common way to address hydrogen sulfide problem in your saltwater aquarium is to remove deposits in your substrate.
The first step is to remove all living organisms to another tank. That includes fish, living rocks and corals, invertebrates like crabs or shrimp, and everything else.
If there are organisms that you can’t remove (for whateve rreason), there are steps you can take to maximize their survival.
- Do the change the brightest lights possible. The lights drive higher oxygen concentrations and the oxygen will help neutralize hydrogen sulfide.
- Add iron supplements to the water. The iron will bind to the sulfide, making it neutral to living organisms.
- Make sure there’s plenty of oxygen in the water. The primary way oxygen enters a tank is through oxygen exchange between the water surface and air. Run a powerhead to circulate water from the bottom to the top for several days before the change.
- Before and during the substrate change, run your saltwater aquarium water through granular ferric oxide (GFO) and activated carbon.
Ways To Prevent Hydrogen Sulfide Problem
One of the best ways to prevent hydrogen sulfide problem in your saltwater aquarium substrate is to run an undergravel filterplate. This will circulate water from your tank through your substrate and properly oxygenating them.
Keep housekeeping invertebrates like hermits crabs or shrimp. They do a fantastic job of scavenging food from substrate surface, before they can slip between the cracks and into the deep.
Sunlight, both visible and ultraviolet, play a pivotal role in breaking down hydrogen sulfide to safe forms. Having proper lighting will go a long way to prevent future hydrogen sulfide outbreak:
- Super High Output (SHO)
- Compact Fluorescent Light (CFL)
- Metal Halide
- LED
Don’t bury live rock in your substrate. Otherwise, the portion that’s buried will die and start to rot beneath the surface. Rather, use dead rocks as a base and place live rocks on them.
Final Thoughts
Like keeping the nitrogen cycle in control (ammonia, nitrite, nitrate), controling hydrogen sulfide is a part of owning a saltwater aquarium. Proper maintenance will go a long way to prevent any serious conditions.