Hydrogen sulphide in DSB

[maroun.c]

Noticed while cleaning up my sump that fuge had some deposited gunk in top of sand bed (4-5 inch sand bed in fuge) fuge gets a lot of flow ( around 8K G per hour) but still as its loaded with algae it has areas of low flow especially on the lower part of the fuge. While cleaning that muddy like deposits I noticed it had a bit of blue color in few areas and that under the top layer of the sand was a more blue layer that I avoided stirring up. Believe this is hydrogen sulphide?
Do you think it's a bad idea to have a DSB under a fuge due to slower water circulation potentially causing more hydrogen sulphide accumulation of release? I'm considering the following:
- making sure algae is trimmed frequently to increase flow
-changing the sand (isolating fuge so no H2S or other nastiest released while cleaning up goes into the system)
-removing the DSB completely.

H2S formation would be natural for DSB I agree but the fact that I have organics settling in on top is what worries me as I believe this leads to formation of toxic stuff on shallow part of the sand bed which can get released in water more than it would in typical DSB .
Thanks

 

[DaveMorris]

I have always used a large and varied selection of small critters in my DSB regardless of whether it is in the sump or in the display tank to mix up the sand. I think that is very important to help prevent that stagnant build up that often happens. Worms, sandbed clams, hermits, stars, snails (Nassarius), cucumbers, etc. All are valuable additions to a healthy sandbed.

 

[maroun.c]

Thanks for your reply, yeah makes sense. I had skipped snails in the sump as I didn't wan to risk them going into pumps and jamming float switches... guess I'll add a few hermits and maybe some shrimps that should help with the build up.

 

[Randy Holmes-Farley Verified Community Expert]

The dark coloration may be metal sulfides. Did it smell?

If it is, stirring it up is not a good idea, but leaving it in place could be OK.

I discuss it here:

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

 

[maroun.c]

Thanks for the link. Great article.
Yes it caused a bit of smell when I uncovered a small part. Made sure not to stirr the sand when I saw it.
Would adding hermit crabs cause any risk of they stirred the sand too much? It is a normal occurrence in DSB right or is it a sign of lack of water movement in the sand of the fuge?
Thanks