Reef Maniac

Deep Sand Beds (DSB)

  1. Reef Maniac

    Reef Maniac MASA Contributor

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    Reef Maniac submitted a new Showcase Item:

    Deep Sand Beds (DSB)

    Read more about this showcase item here...
     
    Last edited by a moderator: 12 Mar 2016
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  3. Tobes

    Tobes Retired Moderator

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    Thanks Hennie, easy to read and to understand. Will help the noobs a lot. Well done Uncle!
    Posted via Mobile Device
     
  4. lanzo

    lanzo Sponsor

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    Very nice....Thanks hennie:thumbup:
     
  5. Broder

    Broder Mudshark

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    Thanks for the beautifully written, easy to understand introduction to DLSB. There are a couple of things that I'd love to hear your thoughts on:

    1. Do sand beds have a life-span of usefullness, ie. should they be replaced after a set time? Or should we just monitor the visible organisms, and take action if their numbers dwindle?

    2. How does the efficiency of a DLSB compare to an algal filter where nitrate is converted with the process of photosynthesis into oxygen? This question is not aimed at promoting one over the other as they're both, IMO integral in a reef system, but rather comparing rates of absorption.

    3. What is your opinion of esturine mud beds as part of a deep live sand bed. Are the particles too dense to allow any real bacterial action between it and the water, considering that there isn't much "stirring" going on by critters?
     
  6. Reef Maniac

    Reef Maniac Thread Starter MASA Contributor

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    thanks guys - this is actually an old article which has been on MASApedia since it's inception - Viper asked that we move our articles into this forum - that's all that I've done at this stage :whistling:

    As with just about everything else in this hobby: "It depends..."

    My DLSB (well, a large portion of it...) is now more than 10 years old. I have added some more sea sand over time, just to increase the depth a bit, but the bulk of the sand is still the same old stuff I collected off the beach at Jongensfontein (near Stilbaai) when I started this hobby. When I moved to Bloemfontein from the Cape south coast some 6+ years ago I transported the DLSB in some buckets, and just carried on using the same sand, with some river sand added when I changed to a larger tank at the beginning of 2005. Each time I moved the sand I did lightly rinse it in old tank water, but it still looked pretty dirty after the rinse. Five years since last disturbing the DLSB, my tank's ammonia, nitrite and nitrate levels are still below the detection limit of our hobby-type test kits...

    To answer your question, I believe that a DLSB can remain viable indefinitely, IF you have a large enough bio-diversity in the sand bed, and (of course) if the sand bed is not over-loaded past it's filtration capacity. This implies that one should:

    • not keep "DLSB predators" such as most wrasses, mandarins, "sand sifting" starfish, gobies, etc. if the DLSB is in the display tank. If it is a remote DLSB, then of course this does not apply.
    • replenish the sand-living fauna from time to time, either by adding small quantities of sand from fellow reefer's tanks or by adding small bits of fresh live rock rubble. Ideally, one should try to get some of the "grunge" left over on the bottom of the boxes that LR is shipped in to the dealers.
    • not over stock one's tank, especially with fish.
    • maintain a refugium of some kind (in-sump or dedicated) to help replenish the life in the sand bed.
    I'm biased towards the DLSB, so don't take my word as gospel ;) but I believe that a mature, well set up DLSB is more efficient than an algae scrubber of the same volume. It is also cheaper, as you do not need any additional lights or pumps to make it work. As stated in the article, a DLSB can also remove/bind toxic heavy metals (better than an algae scrubber, I believe...) On the other hand, an algae scrubber does remove more phosphates than a DLSB, so the ideal would be to have both, or at least to also have a good growth of algae in a refugium.

    A properly graded DLSB must contain a (small) percentage of mud, but I would not use a mud bed as part of a DLSB. Used separately (in it's own chamber in the sump, or wherever), it can be beneficial, but then one must have the correct mud-living animals to live in it. Research by amongst others Dr. Rob Toonen (if memory serves) has shown that the largest bio-diversity of infauna is achieved in a rather specific sand gradation, and that there are relatively few animals that live in the mud. The mud bed can be much shallower than a conventional DLSB, though, so in some cases it might be the best option to use. I have never tried a mud bed myself (yet...), but envisage that a mud bed on the bottom of a "settlement chamber" could be quite useful, especially if it contains one or two mud- or sand prawns that can filter-feed on the settling detritus.

    Hennie
     
    Last edited: 6 Feb 2010
  7. lanzo

    lanzo Sponsor

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    i have a mud bed just before my DSLB.... The amount of pods/bristlewroms in my MB is much more than on my DSLB.

    Can this be due to all the solids settling on the MB first or does it have something to do with the minerals or the tecture of the mud that they like more?
     
  8. Broder

    Broder Mudshark

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    My finding is the opposite of Lanzo's. The mud bed in the DLSB started off with a lot of life in it, including prawns and worms, but gradually these died off, and it now appears dead on the surface. I'd love to have access to a microscope to "scope" the bio-diversity, if any, that is left.
     
  9. Warr7207

    Warr7207

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    cool thread
     
  10. Reef Maniac

    Reef Maniac Thread Starter MASA Contributor

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    I would guess it's the free food - always good for attracting a crowd :whistling:

    Seriously, though - you are describing animals that live above the sand/mud bed. The real infauna which lives IN the sand- or mud bed would be creatures such as worms, microscopic multi-celled and single-celled organisms, and bacteria - also various forms of algae within the top 10mm - 20mm of the bed. Because of the small size of the mud particles, it will pack very dense, and restrict both the movement of larger small critters such as the various worms, and the penetration of water (thus restricting the availability of food and oxygen).

    I have not done so for a while, but I regularly check the microscopic life in my DLSB. On average, I find between 5 and 20 microscopic critters in every drop of water taken from about 10mm below the surface of the bed (and that excludes the "giants", such as small bristle worms, which just does not fit in a drop of water...). I can really recommend a microscope for anyone interested in the complete marine system - it certainly opens up a new world of life-forms which would otherwise have remained unknown.

    Here are some examples:

    A single grain of sea sand - note the smooth, rounded surface, the cracks/fissures in the grain, and the growths of micro-algae:

    [​IMG]


    A foraminiferan (the curled tube in the middle of the photo), a micro-starfish and a ciliate-type gogga to the right. There are at least two other critters visible (although out of focus):

    [​IMG]


    A micro-flatworm busy eating detritus, and another micro-starfish:

    [​IMG]


    An unknown "gogga":

    [​IMG]


    A bristleworm larvae:

    [​IMG]


    Hennie
     
  11. Mauritius-aquarist

    Mauritius-aquarist

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    Hey reef maniac, really nice to share the pictures, frankly fantastic:thumbup:
     
  12. Neil H

    Neil H Moderator MASA Contributor

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    Wonderful article Hennie,

    Perhaps a Doff question ..... the fish produce the waste, the bacteria convert the waste to something not hamfull to our systems... what is this "something"? with a LNS (yes i know i keep going on about this) the bacteria produce mulm as the less harmfull waste which ... what is the DLN version of mulm?? or do i have the cat by the tail???
     
  13. Warr7207

    Warr7207

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    WTF. Is this some sort of Mixt talk ?
     
  14. Neil H

    Neil H Moderator MASA Contributor

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    :lol: I honestly wish it was ..........

    a correction to my statement is that DLN should be DLSB.... bloody :peroni: got the better of my typing fingers
     
  15. Reef Maniac

    Reef Maniac Thread Starter MASA Contributor

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    No, quite the contrary :whistling:

    Definition in About.com:

    Definition from The free freshwater and saltwater encyclopedia:

    From Albert Thiel's book "Small Reef Aquarium Basics", written some 20+ years ago:


    So, depending on how you define it, mulm is either the un-decomposed fish waste (although I would rather define that as detritus), or the totally mineralized (cannot further decompose) remains of the processed detritus (which is the definition I prefer to use).

    After working for some years, the deep sand bed certainly looks VERY dirty when disturbed, and one could be forgiven for thinking that this "waste" is totally bad, and the cause of all evils in the tank. IMHO, the contrary is actually true - let me explain...

    A large percentage of the fish waste (and other primary waste, such as coral slime...) is removed by the protein skimmer. The rest of this detritus settles onto the DLSB, where it is processed by the sand-living organisms. Each organism can extract between 10% and 20% of the nutrients that it eats. So, lets say that (as an example) a large bristle worm eats a piece of fish poo. The worm's excrement would thus contain (say) 90% of the nutrients that the fish poo had. Now a copepod eats the worm's poo, and deposits it's waste which now only contain (say) 80% of the original nutrients. If this food chain is long enough (and in a healthy, well set-up DLSB it can easily be...), it would only take five to ten critters to change the detritus into mulm. This mulm looks bad if the sand is disturbed, but it has now become pretty inert.

    Judging from personal experience, the mulm does not accumulate indefinitely, because there is no visible build-up on my sand bed after all these years of being in operation (or perhaps it is still building up, and will only become visible after (say) 15 or 20 years, who knows...).

    Here's another (contradictory) thought - perhaps the mulm does break down into it's chemical components - but this would not be a bad thing either... Why pay a lot of money to dose various mineral additives (trace elements...) if the mulm is supplying these in minute, but constant, doses? Perhaps this is the reason why my tank has been doing so well for so long, without ANY additives apart from alkalinity, magnesium and calcium...

    Hennie
     
    Last edited: 7 Feb 2010
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  16. RiaanP

    RiaanP Moderator

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    What happens to the end result of detritus?

    Copied from an article on Cryptic zones from Latest | Practical Fishkeeping

    So this is mostly the dirty stuff you see when you disturb a DSB.
     
  17. Warr7207

    Warr7207

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    Thanks
    hamfull and LNS ?
     
  18. Reef Maniac

    Reef Maniac Thread Starter MASA Contributor

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    You're being difficult now :whistling:

    First one is obviously a spelling mistake (come on, you knew that...)

    LNS = Low Nutrient System - in other words, those bright, multi-coloured frag menageries that everyone is trying to create (sorry Neil :biggrin:) MASA has a whole section dedicated to this: Low Nutrient Systems - LNS / ULNS - Marine Aquariums of South Africa

    Hennie
     
  19. Warr7207

    Warr7207

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    Sorry I didn't know these. In the context of the post, I couldn't see that it was a spelling mistake.

    Probably don't know LNS, cause I have never tried to run a Low nutrient system, I believe in having lots of FAT fish :p
     
    Last edited: 7 Feb 2010
  20. Reef Maniac

    Reef Maniac Thread Starter MASA Contributor

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    Ja, you know how these geologists are - spend 99.72% of their time talking to rocks, so we can't expect then to be able to spell, you know :biggrin: :biggrin: :biggrin:

    Ducking now, cause Neil is much bigger than me...

    Hennie
     
  21. Neil H

    Neil H Moderator MASA Contributor

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    ok ok, so a geologists spelling is shit .....

    thanks Hennie et al for the explanations ....

    From what i am reading mulm is referd to as something slightly differently in the LNS .... but again, everything you read is slightly different, which one do you believe ???

    " in other words, those bright, multi-coloured frag menageries that everyone is trying to create (sorry Neil :biggrin:) "... ag neee man Hennie, they are not all like that i really believe it is the way of the future ....:):)

    Warr, LNS does not mean low feeding, ironically LNS is perhaps one of the poorest descriptions i have every come across, in reality LNS should be renamed to something like a NNS (natural nutrient system) or RNCS (rapid nutrient cycling system)..... any healthy marine system has plenty nutrients, a LNS system simply cycles these nutrients extrememly efficiently, this can be achieved with the zeo system (which scares the shit of of everyone because of all the technical terms and dosing regieme.....) OR with an extremely well maintained and well functioning DSB.......

    Sorry mods if i have taken this thread off topic, feel free to move some of this across to the evil LNS section:razz::razz::razz:
     
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