DSB’s....again!

There's a DSB debate raging in the Buy/Sell/Trade forum, so I thought I'd start a new thread here to continue it.

DSB's are a hot topic, and, I think, an interesting one.

From what I've gathered, Ron Shimek is pretty much the "father" of DSB's and is often cited in most any DSB discussion. Here's his "official" formula:

http://www.rshimek.com/reef/sediment.htm

The gist of a DSB, according to him is this:

In order for the sand bed to filter the aquarium water, water has to move into and out of the sand bed. The micro-organisms in the sand bed are what do this. Anything which we do (like vacuum the sand) or which animals do to disturb those orgranisms reduces the effectiveness of the sand bed.

The key components are:

1. Very fine particle size, because the organisms which make the DSB work require it.

2. 4+" deep

3. As many detrivore kits as you can afford

4. NOTHING which will disturb the population of "infauna"

5. Yearly detrivore kits to "recharge" the sand bed populations

"The depth of the sand bed should depend on the particle size" is said everywhere. It's true that in order to keep the water current from oxygenating the sand bed it needs to be deep enough to keep the oxygenated water out. Fine sand can do this with less depth than coarse sand.

However, what actually moves the water in and out of the anaerobic zones, which allows the DSB to filter the tank water, are organisms which can't live in coarse sand. Without those organisms, the DSB can only get rid of whatever nitrates diffuse into the sand or already existed in the water in the sand when the sand bed was installed. Obviously, that's much less than using Ron's formula.

Based on that, it's easy to see why people can have a DSB and still have nitrate problems.

Not only that, but if the organisms Ron talks about can't live in a sand bed, then that sand bed can't process the detritus that accumulates there. And then suddenly your DSB is the "nutrient sink" that people complain about.

Ok, now for Part II of this book!

I don't like DSB's. The parts about "cannot disturb the sand" and "buy as many detritivore kits as you can every year" (mucho dinero) turn me off. I understand how a DSB is supposed to work, and I believe Ron when he says it does, but given that there are plenty of successful tanks without them, I would rather avoid any potential trouble and the cost of the extra sand and detritivore kits.

I like burrowing animals like jawfish, and I like cucumbers and sea stars, and I like hermit crabs and shrimp (yes, Ron has said hermit crabs are bad for sand beds). Plus, the play-it-safe side of me doesn't like the idea of accidentally disturbing a pocket of hydrogen sulfide if I drop a rock into the sand.

So, to end this huge post, I am wondering the following:

Hobbyists often use sand that is too coarse for their DSB, and we almost always use at least SOME creatures which prey on sand bed infauna (like hermit crabs). Does that concern anyone but me? What keeps the DSB from becoming a detritus trap, etc. if we don't have the organisms a DSB really needs?

I'm curious what all of you have to say!!

-Tom

I personally say NO to dsbs. First I think they are ugly. Second I can't see paying extra for bugs and whatnot just to get rid of nitrates. I have 1.5" of sand that is constantly stirred by my goby and my nitrates are zero. Third there have been numerous people tell their story over on Reef Central and other forums I visit of their tank crashing at about the 4 year mark. Here is one thread that is only 85 pages long discussing this. DSB link

I say a MSB (medium sand bed) is better because.... Ummm.... it's in between! Personally speaking, we really don't know which is better. That's what I was trying to say in my previous post. What works for Adam will probably not work for anyone else . And what was my experience will probably not be yours. We in this hobby are all learning so much now, I just think that a fear factor is not healthy to the hobby. Unless it is well warranted. I know that there are reefers in our own back yard that have had DSBs for longer than 3 years without a crash. Then again, I know there are some that have had "normal" sand beds who have crashed. Could it be because they fed their fish a teaspoon of food one day?

Carl - Good points! I agree. Whatever particle size we use can still be beneficial and can still host some forms of life.

>> "deep enough for you to host life and feel comfortable with it"

That's really the bottomline for me. In the end, I want to feel comfortable with the decision. To me, IMO, I would feel more comfortable with a shallower sand bed that can be disturbed and burrowed in without ever having to worry about hurting infauna populations and disturbing anaerobic zones.

KeoDog - I agree too! I like the look of a shallower bed better. And like you said, LOTS of people have had bad experiences with them. Which leads me to...

Mark - You're right: I don't disagree with any of those questions, and I DO agree that a sand bed is useful. I also agree that a DSB can be useful. However, given the knowledge and experience of some people who have had bad experiences with them, it's hard for me to want to take a risk. That coupled with the fact that I like the look of a shallower bed better leads me to believe that I will have more comfort and satisfaction with my tank without a DSB. That's just me!!

One thing I have definitely learned since starting this hobby is that opinion is inseparably connected with why we do what we do. Many experienced hobbyists don't agree on everything, yet what they do works. There is no "right way," and with so many things (like DSB's) there's very little actual knowledge on the subject and people's experiences support both sides of the issue. Thus, the choice to have one or not, for me, IS based on opinion, and that's why I asked what everyone thought.

Because there are successful reef tanks with and without DSB's, this isn't a debate that can have a winner. It's not even really a debate, and my intention isn't to try to start one. My intention is to collect opinions on the subject so I can make a better decision. Mark, I am particularly interested in your response to Shimek's article (in particular about the grain size), because your opinion carries more weight because of your vast experience.

It'd be really cool if we could make a list of all the pros and cons of a DSB. Here's a first pass:

PROS
- Properly setup and maintained, a DSB provides much greater filtering capacity than a shallow bed or none at all
- Some people like the look (I haven't really heard many people say this, but since not liking the look is a con for some, I figured I'd include this).
- Lots of aragonite substrate may be a source of Ca and buffer for the system

CONS
- More expensive than a shallow bed or none at all (lots more sand + detritivore kits)
- If not properly setup and maintained, the DSB MAY crash. (This is where I could use some help.....)
- Some people don't like the DSB look
- The DSB takes up more space. 4" of sand makes the system 4" shorter.
- Some people like sea stars and other burrowing animals which reduce the effectiveness of a DSB

Is there anything else?

Thanks for the responses!

-Tom

I do enjoy watching worms in the sand, for a little while !

A quick skim through Ron's article http://www.rshimek.com/reef/sediment.htm refreshed my memory of it so that I could tell you how it fits in with my own experience.

Having seen quite a few good tanks operating in so many different ways, including Berlin style tanks with LR but absolutely no substrate, Ron is at one point of the "spectrum".
It is my observation from my little window of perception, that if there were no "spectrum" we would all live very monochromatic lives. I love the beauty and variety in which the world was organized and give full credit to its Creator. In the systems that the Creator has allowed me to have, I have tried to use all the natural processes that were known to me, and available to enhance the aquariums success.

In addition to many of the common techniques and processes, I've used some successful techniques that are a little less common:
- direct natural sunlight
- sponge refugia
- surge circulation

Whatever we do with our aquariums one thing is certain, we seem to be enjoying it.