Deep Sand Bed -- Anatomy & Terminology

[tmz]

For instance hydrogen sulfide breaks down very quickly when it reaches oxygenated areas, so unless you go digging deep in your sand bed it won't be an issue. It also is extremely odiferous so you'll know right away if it is getting released. If you can't smell it, there is not enough of it being released to harm anything. Given continued presence of sand worms it would have no greater concentration in an old tank than a 2 year old tank.


Define quickly. Several hours to a day is long enough to do a lot of damage.HS- can be deadly in parts per billion so a good nose isn't a safe indicator,imo.. While most can smell it at low concentrations human sensitivity to the odor varies as does the H2S portion.

http://reefkeeping.com/issues/2005-12/rhf/index.php

from it:

Hydrogen sulfide has a strong "rotten egg" smell. The odor of H2S can be detected in the air by humans at levels as low as 0.5 to 300 ppb. The large variation in range indicates that some individuals are very much more sensitive to it than others.


and

is by inhibiting a mitochondrial enzyme called cytochrome c oxidase. It can be inhibited at hydrogen sulfide levels in solution as low as 30 ppb.12 Such inhibition limits the ability of mitochondria to produce energy for cells. Another enzyme, catalase, is inhibited at concentrations of 6,000 ppb.12 Other mechanisms of toxicity are also likely, and have recently been studied.

and

sediments are the most likely place for hydrogen sulfide to be produced in a reef aquarium.

marine sediments often accumulate hydrogen sulfide and deplete in sulfate. This zone often starts a few centimeters below the surface, and can extend up to a meter or more before the sulfate is fully depleted. Below that depth, other processes take place, such as methane production.

and


I'll comment on clumping/clogging and other points a bit later. It's not as simple as maintaining aquarium ph.

 

[rivoth]

The key to hydrogen sulfide is simple. Don't make rapid large scale disturbances in the sand bed. Some of the recommendations I've seen to replace or siphon sand have the potential of doing exactly that so don't do it.
Be wary of fish that love to dig around in the sand. A good idea anyway since the same fish are usually predators on the sand bed infauna.

It cannot be emphasized enough that the key here is the fauna populations in the sand bed. They provide a slow, controlled, and very steady mixing and breakdown of all gases, food, and dissolved chemicals in the sand bed. They won't prevent the existence of hydrogen sulfide, but they will prevent it from building up in ever increasing levels via multiple mechanisims. First they allow the slow, steady mixing of the gas with oxygenated regions of the sandbed where it can safely break down. Second they eat the organic compounds that are part of the hydrogen sulfide cycle so there will be less of the gas to start with.

The bottom line is that hydrogen sulfide exists, but it is safely separated out of harms way if you practice reasonable husbandry.

 

[Paul B]

The bottom line is that hydrogen sulfide exists, but it is safely separated out of harms way if you practice reasonable husbandry.

This reminds me of my first day in Viet Nam. I jumped off a helicopter into a large clearing in the jungle. I asked where I was supposed to sleep and the Capt. showed me my place. It was on top of about 400- 8" artillery rounds. If you don't know what they are, they are artillery shells about 3 feet long and weigh about 40 lbs. Anyway, he said, don't worry, they are safe as long as you "practice reasonable husbandry".
A week later we were attacked and even though that was about 45 years ago, to this day, there is a hole in the ground in that spot about 60' across and 15 feet deep.
That is an analogy I like to use when referring to DSBs and hydrogen sulfide in general.
That taught me a couple of things, don't sleep on artillery rounds in a war and don't install a DSB :lol:

 

[cloak]

I'm not really sure if this pertains to a DSB, but having kept one for 9 years, there were a few times when I would do a large water change and get a strong rotten egg smell. I was only changing out 15 to 20 gallons on a 60 breeder, so the water level only dropped by about 6" or so. I'm guessing this odor came from the live rock that was now exposed?
Sorry if this is sort of OT. I'm just trying to put some of the pieces together. Thanks.

 

[Paul B]

No, that odor was coming from hydrogen sulfide in your DSB. Exposed rocks smell like wet rocks.

 

[rivoth]

That taught me a couple of things, don't sleep on artillery rounds in a war and don't install a DSB :lol:

Your humor is a lot of fun and completely irrelevant

 

[cloak]

No, that odor was coming from hydrogen sulfide in your DSB. Exposed rocks smell like wet rocks.

How come it didn't smell like that everytime I did a water change then? Instances like this were few & far between in a 9 year period. If it was my DSB, I would think that the smell would always be there, no matter where the water level was at. That wasn't the case.

 

[Paul B]

I don't really know but I have had hydrogen sulfide many times in many tanks and the smell is unmistakable. It can only come from an area that is without oxygen, the rocks should not be able to produce it except where they touch the sand.
If your watwer changes moved a rock off the substrait, it could have come from there. Rocks on sand often produce that gas. Where I collect is a muddy lagoon and all of the rocks have hydrogen sulfide under them. If detritus builds up under rocks it will produce it. DSBs have no circulation so they are prone to it.

Your humor is a lot of fun and completely irrelevant

Oh, OK then

 

[cloak]

No rocks moved as far as I know. The rock structure was built on top of the sandbed, so they were stuck in there pretty good.

 

[Paul B]

Then I have no Idea

 

[elegance coral]

Hydrogen sulfide can be produced in porous LR. If rotting organic matter is permitted to build up in the holes of the rock, then the water level drops, the rotting organic matter along with the hydrogen sulfide, can drain from the rock. At this point the smell would be obvious.

The easiest way to remove the threat from hydrogen sulfide is to keep the system clean. Rotting organic matter is the fuel used to produce hydrogen sulfide. If there is very little rotting organic matter, there is very little threat from hydrogen sulfide.

 

[Paul B]

Yeah, what he said

 

[drukkosz]

good to know

 

[cherubfish pair]

Although I haven't read the whole thread, I'm interested in opinions on having a dedicated remote DSB for one big queen conch.

 

[Virtuoso]

Okay, so I have read what I think was all of this thread over a couple of sittings and I have been keeping an eye out on the forums to see what the general consensus was and I still don't really have a clear understanding. Should a first-timer be setting up his or her new tank with a DSB? Would a DSB in the fuge be preferable?

 

[rivoth]

You won't find a general consensus because there are many ways to run a marine tank and people can get a bit religious about their preferred method.

I would recommend a DSB for somebody who wants to try and build a diverse eco system. If you don't like the idea of little bugs, worms and detritus in the sand then go with a shallow sand bed or a bare bottom.

A DSB also requires that you avoid animals that are sand bed predators. Many gobies, crabs, sand sifting stars fit into this category.

A DSB works best in the main display tank. The creatures in it require food and the display tank is where you'll be doing most of your feeding.

Dr. Ron Shimek runs a DSB in his 40 gallon breeder, but does not recommend a tank that small. It's hard to maintain good bio diversity in a tank with that little sand surface area. I would definitely not go smaller than that.

In the end you have to decide for yourself what interests you about the hobby. There is no beginner setup, all marine aquariums are complex systems that take a while to learn. Expect to bang your head against the wall a few times. Make your decision and accept advice from those who have success with that type of system. If you let yourself be pulled in too many directions by all the different opinions on this site you are guaranteed to fail.

 

[Virtuoso]

rivoth,

Thank you for the reply. Unfortunately I had a feeling that was the way it was going to be. I think in the end, unless I read something that convinces me otherwise, I am going to run without a DSB. It seems like it adds a lot of extra complexity and the possibility of something else going wrong. I had heard the bit about it needing to be a larger tank, but I have also seen a ton of people saying they put it in their smaller fuge and that it helped. I don't think I will do one in the fuge, with the reason being if I decide later on down the road I want to add one I'll go ahead and do it then. I think it would be easier to go "oh, this and that chemistry is off and seems to be fluctuating a lot" and then add it, rather than have it and not notice if it is doing something or just sitting there.

Thanks again.

 

[Scopus Tang]

Dr. Ron Shimek runs a DSB in his 40 gallon breeder, but does not recommend a tank that small. It's hard to maintain good bio diversity in a tank with that little sand surface area. I would definitely not go smaller than that.

I have DSBs in both a 20gal long and a 29gal high, while I would agree that overall biodiversity of critters may not be as high as in my larger tanks, I would argue that both sandbed in the smaller tanks do a good job of carrying a variety of microbes and worms. Truth be told, none of my tanks have a foot print larger than the 40B (same foot print as a 65gal or 30B), and all have successful DSBs running in them, although none of them are over 10 years old. The oldest was originally set-up in the fall of 2001 and the tank has been reset a number of times since, but the sandbed has remained untouched.

 

[NEK-ap24]

Thoughts on a Display DSB

Thoughts on a Display DSB

I have an Osaka 155 tank, and looking for a larger one, both of which are very tall. I am looking at graduating from my AP24 set up with large refugium.

I am considering going with the ecoxotic LED lighting, however I am concerned that I will not get the best light penetration down 24 inches to the bottom of the tank.

I was thinking a DSB would effectively raise the bottom 5 inches, and be benifical as well.

I have heard some concerns with having a DSB in the display tank, rather then the refugium.

Any thoughts?

 

[elegance coral]

I have an Osaka 155 tank, and looking for a larger one, both of which are very tall. I am looking at graduating from my AP24 set up with large refugium.

I am considering going with the ecoxotic LED lighting, however I am concerned that I will not get the best light penetration down 24 inches to the bottom of the tank.

I was thinking a DSB would effectively raise the bottom 5 inches, and be benifical as well.

I have heard some concerns with having a DSB in the display tank, rather then the refugium.

Any thoughts?

Well you asked. LOL

I have a large haddoni in my display, so I believe it's important for me to have a DSB. I have stony corals and other very delicate creatures in my tank, so I can't afford to have a rotting, bug infested, compost pile on the bottom of my tank. About once a month, when I do a water change, I vacuum all of the sand with a gravel vac. This removes the detritus and keeps the sand sparkling white. It's amazing how much light reflects off the white sand and back into the tank. I have ledges and over hangs near the sand, and they are much brighter underneath than the caves in the rocks further up. If you allow your sand to become choked with rot and decay, like a Shemik sand bed, you don't get that reflected light, because the sand turns ugly and brown. So, IMHO, a deep sand bed will help move the critters closer to the light. If you keep the sand clean, it will also reflect a great deal of light back into the tank, further increasing the PAR your corals are exposed to.