Help with denitrate reactor

[renato120]

I have an aquamaxx denitrate running for over 6 months, I notice that the media is getting black.
Is this normal? Should I change to a new one?
I had that rotten eggs small a few weeks ago, so I open the drip rate all the way. Smell went away. I just changed back to 3 drips per second.
I dont think The black coloration is right tho.
Any ideas?
Thanks

 

[renato120]

Up

 

[Randy Holmes-Farley]

The black is likely metal sulfides precipitated when the flow was too low and you generated hydrogen sulfide. It probably won't redissolve.

I discuss metal sulfides here:

Hydrogen Sulfide and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-12/rhf/index.php

Stability of Hydrogen Sulfide in Water: Metal Sulfide Precipitation

Sulfide in seawater is also unstable toward precipitation with certain metals. The black deposits often seen in anoxic sediments are typically metal sulfides, especially ferrous sulfide (FeS) and pyrite (FeS2), with much smaller amounts of copper, manganese, zinc, nickel and cobalt sulfides. The exact processes whereby these metal sulfides form in marine sediments and elsewhere is complicated and still under study. In some areas, like the Orca basin in the Gulf of Mexico, deposited iron sulfides make up as much as 0.7% of the sediments' mass. So, iron sulfides are not necessarily a trace component.

 

[renato120]

The black is likely metal sulfides precipitated when the flow was too low and you generated hydrogen sulfide. It probably won't redissolve.

I discuss metal sulfides here:

Hydrogen Sulfide and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2005-12/rhf/index.php

Stability of Hydrogen Sulfide in Water: Metal Sulfide Precipitation

Sulfide in seawater is also unstable toward precipitation with certain metals. The black deposits often seen in anoxic sediments are typically metal sulfides, especially ferrous sulfide (FeS) and pyrite (FeS2), with much smaller amounts of copper, manganese, zinc, nickel and cobalt sulfides. The exact processes whereby these metal sulfides form in marine sediments and elsewhere is complicated and still under study. In some areas, like the Orca basin in the Gulf of Mexico, deposited iron sulfides make up as much as 0.7% of the sediments' mass. So, iron sulfides are not necessarily a trace component.

Thanks for the reply! I guess I will remove it. Its toxic.