hydrogen sulphide :(

[CutthroatKid]

well... I discovered two fairly large (at least 6") pockets of H2S in my tank. I think when I moved the tank the sand (3-3.5" deep) shifted and trapped stuff in spots causing it. After reading lots threads about it, I can't decide if I should wait and see, or tear the tank apart before it crashes.

Help please

[charlie]

Can you give me a call tonight James? Try after 7PM. Not a good situation!!!!

[CutthroatKid]

ok. thanks.

[DevonM]

Hey James,

Could you explain a little bit about what you are experiencing? How are you diagnosing the problem? I would like to know what you're going through, it's a new issue for me.

Best,
Devon

[CutthroatKid]

I see no effects on the water or livestock, but I did notice a gray area in the sand. so I took a syringe thing I use for feeding and stuck it down in there (very careful not to stir it up) and took a water sample. Smells like rotten eggs (sure sign of H2S) then check around the tank for any other areas.
I don't know much about it other than what I've read, and I had to take an H2S safety course when working the oil patch but that is airborne H2S.
I'll let you know what Charlie tells me as well...

[CutthroatKid]

Guess I'm going to tear it down and change the sand unless there is another option...
Any input will help. Even if tips on the sand change.

[DevonM]

Guess I'm going to tear it down and change the sand unless there is another option...
Any input will help. Even if tips on the sand change.

Maybe you should post this problem in another area, or have Chalie move it. There are probably some other people out there who have dealt with this.

[Ninong]

Reef Aquariums actually is the right section for his post.

So you have two 6" diameter patches of hydrogen sulfide beneath some rocks? How deep are these black patches?

H2S that is deep down in a deep sand bed is not a problem unless it is released suddenly all at once. H2S does not belong on the surface of a sand bed. This condition is rare in a 3-3.5" DSB that is fully functional and populated by diverse infaunal populations. Somehow the area beneath those rocks became anoxic.

How large is your tank? What is the composition of your sand bed? Can you see the sand bed through the front glass? What does it look like? Are there a lot of worm tracks?

I doubt that your tank will crash and I doubt that you will have to take down your tank. You may be able to 'fix' things. Are these rocks at the base of a large structure? In other words, do you have to take down the entire reef to get at them?

[CutthroatKid]

Thanks for the post Ninong. I got it a little too late though...
It is a 55 and the sand was 90% sugar sand 10% crushed coral. There were some worm tracks, but not many and when I was cleaning it, I found out I didn't have nearly as many nassarius as I thought (8 in the whole tank).
When I took it apart though, I'd say 60% of the sand was black...

[denhay14]

What does black sand mean?

[charlie]

What does black sand mean?

Exactly what the title of thread is. A little is OK, 60%, and you are sitting on a ticking time bomb.
Good call on changing this out James, while you had the chance. JMHO

[Ninong]

Definitely a good call on changing it out if "60% of the sand was black."

[Ninong]

Dr. Ron Shimek has written several articles on deep sand beds over the years and some of them are still available online. These articles include information about sand bed animals , plankton produced by sand beds, the importance of sand beds to reef tanks , as well as refutations of some of the misconceived criticisms of sand beds.

(P.S. -- Here's another article by Ron Shimek that I finally found: How Sand Beds Really Work.)

Dr. Rob Toonen wrote a very nice two-part article on deep sand beds back in 2000: Are Plenums Obsolete? Part 1. and Are Plenums Obsolete? Part 2. Rob also ran some experiments on sand beds a few years back and the results were published: Feature Article: An Experimental Comparison of Sandbed and Plenum-Based Systems. Part 1: Controlled lab dosing experiments. and Feature Article: An Experimental Comparison of Sandbed and Plenum-Based Systems: Part 2: Live Animal Experiments.

Those articles will give you a good background on how a functional deep sand bed works and what is necessary to keep it working. I had no problems with my DSB but it was 6" deep in a 120-gal tank. And, I spent a fortune (~$650) on acquiring what we would call "detritivore kits" and live sand from several different sources.

I found Rob's two-part article from 2000 the best description of exactly what happens in a deep sand bed, so that would be my recommendation for what to read first.

Ron Shimek wrote another article on sand bed's that I can't seem to find right now. Some of his online articles seem to have disappeared.

I would save Rob's two-part article reporting on his experiments for last. However, for anyone who hasn't yet purchased their sand or decided exactly what they want in a sand bed, that article should be read before making any decisions. I'm still a very big fan of deep sand beds, but the results of Rob's experiments are counterintuitive in some respects. Yes, smaller particles win out over larger particles but his experiments showed that even shallow sand beds do provide a significant amount of denitrification.

All of those articles are interesting reading and if I can find that other article that Ron wrote, I will stick it in here later.



Dr. Rob Toonen's website
List of articles

Dr. Ron Shimek's website
List of articles

Both of these artilces are related to sand beds:

• Feeding Begets Food, 1 or… Food Production By Design, How A Deep Sand Bed Can Produce Food For Reef Inhabitants.
  
  • http://www.dtplankton.com/articles/sandbeds.html

• Feeding Begets Food, 2 or… Food Production By Design, Using A Refugium To Produce Food For Reef Inhabitants.
  
  • http://www.dtplankton.com/articles/refugiums.html

[Ninong]

What does black sand mean?

Black sand means that there was little or no oxygen in those sediments and hydrogen sulfide was produced by obligate anaerobes using sulfate (SO4) as an electron receptor. I don't expect you to understand this unless you have already taken basic high school chemistry, which I doubt at your age.

Have you ever walked along a mud flat area at low tide and noticed a rotten egg smell? The rotten egg smell is hydrogen sulfide (H2S). You may have to kick your foot into the sand to release the smell. Sometimes it's just half an inch below the surface in areas that are stagnant with very little oxygen.

There are different types of bacteria that live in the sand under the water. The top layer of sand has lots of oxygen because the water flowing over it has lots of oxygen. Oxidation takes place there because the aerobic bacteria use oxygen as their preferred electron receptor to complete their metabolic processes (respiration). You're going to need a big dictionary here.

As you get down deeper into the sand bed, there is less oxygen because the bacteria on top are using it all up. So, in the top layer the bacteria use oxygen O2 (aerobic respiration). Then, just under that layer, you have an area with very little oxygen. In this area the bacteria -- called facultative anaerobes -- are capable of using either oxygen or nitrate (NO3) as an electron receptor to complete their respiration. They can switch back and forth between O2 and NO3 depending on what's available. If oxygen is available they will use that but since oxygen is really scarce in that area, they have to be able to use nitrate, too.

Below the area of very little oxygen, you have the area of no oxygen. This area is called anoxic. That just means "no oxygen." In this area obligate anaerobes use sulfate (SO4) as their preferred electron receptor to complete their respiration.

The layer with oxygen can be anywhere from 1cm to 10cm deep. It is usually at least 3cm deep but in really stagnant areas, it might be only 1cm deep.

The thin area between the area with oxygen and the area without oxygen is where denitrification takes place. That's the area inhabitated by facultative anaerobes that are capable of using either O2 or NO3 as an electron receptor to complete their respiration.

I really don't expect you to understand this at your age. If you do, so much the better. If you don't, don't worry about it. Just remember that the rotten smell you get when you poke your foot into dirty looking wet sand is caused by hydrogen sulfide. That's what CutthroatKid had too much of in his sand bed because it wasn't properly oxygenated. In other words, his sandbed was stagnant -- sort of like what you would find in some stagnant areas that smell like rotten eggs.

If you want to understand all of this a little better, check out some of those articles I linked above. A couple of them are easy enough, I think, for your age bracket but some are definitely not.

[CutthroatKid]

Thank you very much for the links! I'll need to read them in more depth when I get back from class.
I'm glad you guys agree that changing it was a good call. I now have about 1-1.5" in the display, and plan on about a 6" remote DSB. I will definately read the articles before I get it running though. I think I might have read some of that plenum article a while back as well.
Thanks again.