Deep sand beds and LR to settle a tank

Discussion in 'Beginner Discussions' started by crispin, 26 Jan 2008.

  1. crispin

    crispin

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    hey guys,
    can you explain to me the principles of establishing a DSB. As in what substrate
    The diameter of particles
    Depth of layers
    and where to source it.

    I assume getting new material from a LFS is the safest and that second hand would have good and bad fella in it anyway, but be cheaper.

    I have read a fair amount about DSB, the theory all makes sence (not much different from me farming my organic farm with trophic levels and micriobes, all be it that I dont want anerobiuc there!) but the science of how to make it I am not sure.

    And do i want to set my NEW tank (cant wait to get it::) up with water only, filters running etc for a while, establish the water, drain it and then add the DSB and then refill tank and let it run through cycles to establish sand bed, then add live rock, establish those cycles and in 4 months look at adding softs and then fish. Is that a simple basic approach?
     
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  3. Kanga

    Kanga Retired Moderator MASA Contributor

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    Here is a pic of how a DSB Works as well as 2 links to MASApedia articles on DSB's and Cycling your tank.




    [​IMG]
    OK you want the rock and the DSB sand in from the beginning, the actual water is not what you want to cycle is the substrate, the DSB and the rock


    Depend if it comes out of a good established system its great, but most wont be willing to give it up. Personally I would start from scratch

    OK there are many many views and here is a few options, sugar fine grain size is ideal

    Live Sand from the sea collected close to rocks under the low water mark (The sea)

    Sugarfine crushed coral (most LFS)

    Aragonite, aragolive (expensive but nice) (Aquality/MASA Sponsor)

    Silica sand/Playsand (cheap make sure you wash it well though)(Reggies, Builders Warehouse)

    15cm and deeper is considered ideal by most


    And here is a pic of how it all fits into your sump

    [​IMG]
     
    Last edited by a moderator: 24 Nov 2011
  4. crispin

    crispin Thread Starter

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    i am slightly confused, what do you refer to the substrate 15-20 cm thick in the main tank....not in the sump?
     
  5. Kanga

    Kanga Retired Moderator MASA Contributor

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    Depth of your DSB, not the substrate in your tank
     
  6. crispin

    crispin Thread Starter

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    does the substrate not work in a similar way?
     
  7. Kanga

    Kanga Retired Moderator MASA Contributor

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    You could have your subrate deeper than 15 cm and it would effectively be a DSB in your display, although it does not generally look nice and takes up space.

    shallower lets say 5cm would be a SSB (shallow Sand Bed) which would be that same as the top layer of a DSB athough you would not have the Aneorobic denitrifying bacteria in the bottom layer as a DSB has. Hence your "substrate" wobnt be converting Nitrate into nitrogen gas which can escape your system

    So IMO your substrate would largely aesthetic and your DSB in your sump would be your filtration
     
  8. LikesFish

    LikesFish

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    To clarify - you can run a DSB anywhere - in your sump, in the main tank, or in a remote bucket. It does not really make a difference. Some people (most on here) prefer to run it in their sumps. I don't - simply because I never have enough room in a sump and/or have a large enough sump to have a decent amount of sand in there. Having it in my main display allows me to have a huge DSB which works properly.

    Not saying you can't use it in a sump, but I only rally saw a big difference in my water parameters when I started using a large DSB - such as in my display. Furthermore, many fish and inverts require a DSB so keep this in mind when picking your live stock when you have your DSB only in your sump.
     
  9. LikesFish

    LikesFish

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    PS: There is no way you will have room for an effective DSB in your sump - the skimmer takes up too much space and the compartment is too small. That is why I had my DSB in the tank itself. Never had a problem.
     
  10. Kanga

    Kanga Retired Moderator MASA Contributor

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    Like fish agreed you can run it a drum, bucket just about anything that will hold water, but from a space point of view most run it in the sump
    Interesting, what livestock would you say need to have a DSB in the tank?
     
  11. LikesFish

    LikesFish

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    Wrasses that bury at night needs at least 6-8cm, when they get larger that needs to be about 15cm. Garden eels. Sand burrowing gobies. Tube anemones. Tube worms prefer it. Etc.
     
  12. crispin

    crispin Thread Starter

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    running it in the main tank didnt seem to detract from the asthetics on the one I saw at "likesfish" place, indeed i found it facsinating to see all the differenht movements of creatchures in the upper layers. but then again covering a large tank with 15cm substrate has a cost effect, and I am not sure that I would be able to contail a decent sized on in the sump area and i would like to make a self contained system for the sump. Does surface area make a difference, or is it more depth.

    That is to say is it better to have a large flat surface area or a deep colum of a bed?

    Also Likesfish was there a differnce in the diameter of you tank substrate and if so, can you give your thoughts on why and how you did it?
     
  13. LikesFish

    LikesFish

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    It is both. The larger the surface area, the more place for bacteria. If a dSB is not at least about 12cm deep, it is not deep enough for anaerobic bacteria to proliferate in a relatively oxygen depleted environment to break down NO3 to N2 gas.

    A DSB won't perform full biological breakdown of wastes if it is not deep enough - so you cannot skimp on that. Make it at least 12cm deep. The size - that you can play with depending on your stocking levels. Unfortunately I have absolutely no idea how large it should be to be sufficient.

    I had 2 DSB's. The one in the big tank is about 10cm - 13cm deep, depending on location. So it is borderline. Cost was the biggest factor - 300kg of sand is not cheap. The 680L tank - the one you are buying - had 15cm deep sand bed of CaribSea oolite sugar sized aragonite. I did this because AFAIK that is the right depth, and having it in the main tank ensured large enough volume of sand to process the wastes produced by my Clown Trigger.

    If I were you, from what I have read (no personal experience on it though), is before I skimp on the size of the DSB due to cost concerns, I'd buy the cheaper play sand (which is not calcium based but silica based), and use that to make a 15cm deep bed in the display tank. It will solve the cost issue. But for details please discuss with some members on this forum who have used this kind of sand - I have not for various reasons, but I might be over doing it by only using calcium based sand.
     
  14. Kanga

    Kanga Retired Moderator MASA Contributor

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    Oh yes, its fascinating for us reefkeepers, i can sit there for hours and watch it, less so for other non aquarists, its just layers of sand with algae and goggas

    You can have a DSB in plastic containers, 25L drums a glass tank anything that will hold water just about

    You do need the 15 cm or so, deeper than that, yes i would imagine there would be benefits but not huge amazingly worthwhile ones (IMO I could be wrong here)

    But surface area is the big one, the aerobic (upper layer) breaks waste down as far as nitrate, then the anaerobic (deeper level) breaks down the nitrate to nitrogen gas. so the bigger your surface area your aerobic area is the more nitrate is available to be broken down.

    Here is another concern for me with DSB in display, 60% + of my display is covered with live rock, hence i would only have 40% of the surface area in my display available for aerobic bacteria.

    Secondly (and this is just my personal feeling) I would not want wrasse etc digging in my DSB releasing those anoxic compounds from the bottom of the DSB into my system.

    But that said its certainly is possible and I can believe it would have benefits but this is why I would not do it
     
  15. crispin

    crispin Thread Starter

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    hmmm lots of food for thought, which indeed is tha value and fun of learning first and making less mistakes later. I guess as I am going to be starting from scratch (i did listen to the views of the forum on that point:)) and i will be cycling slowly and introducing things atleast a number of months away i could run an experiment of doing an external DSB and then doing a DSB in my tank, which is where I think i would head towards anyway, take water quality and publish them on here, might be interesting to see if there is a distinct advantage to water quality, especially as I want to head towards a reef system as my goal.

    Likesfish I am slightly concerned about you.......I have seen that 4m mosnter you have and I cant quite understand how you can tear yourself away from it to be som active on the forums??? Or are you enjoying those beautiful Mantis shrimp in the office? I must admit they were my fav thing to see at your place:)
     
  16. LikesFish

    LikesFish

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    I feel differently on these two points. Firstly, aerobic bacteria is not found just on the surface of the sand layer. It is found much, much deeper too - I am not 100% certain but IIRC up to a depth of about 4-6cm it is still all aerobic. LR on top of or even pushed in to the sand would make no difference. In any case, if the aquascaping is done correctly most of the LR will be above the sand or on its side, and not on the sand, flat.

    Secondly, I have never experienced any issues with my wrasses and eels and groupers etc. all digging in my DSB. Sure if you have a huge grouper or wrasse in a small tank it will damage the bed, but assuming a properly stocked tank I really cannot see any issues. When they dig they go under the sand - that is it. They do not turn the sand over.
     
  17. LikesFish

    LikesFish

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    Ah good that someone worries :) PS It is a 2.7m monster. I am reorganising my photo library so I have to sit in my office. And it is air conditioned :) Every night when I watch DVD I multitask between the movie and the tank, so then I get my large fish fix ...
     
  18. Kanga

    Kanga Retired Moderator MASA Contributor

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    Thats the beauty you get all the views and get to make an informed decision:thumbup:

    I hear what you saying about the aquascaping but i have before lifted smallish rocks and the sand underneath was black, typical of the deeper layers in a DSB.

    The Wrasse etc like i said personally I would not feel comfortable, but I am not saying that it could not work.

    Many people have DSB's in their display, so it has to work! Again its not how I would set up a tank.
     
  19. KevinW

    KevinW

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    Some comments...
    The depth to which the oxygenated layer in the DSB extends is dependent (amongst other things) on water circulation rates and one of the key determinants of that is the grain size of the sediments. Hence coarse sands (large pore spaces) are oxygenated to a deeper level than fine silty sediments (very small pore size between the grains). That is why when you go dig in mudbanks you often find the anoxic layer quite near the surface whereas in a coarse sand sandbank that layer is much further down.

    With regard to the effects that wrasses etc have on the sand bed, they do turn the top layers over. The depth to which they do this depends on the type of animal that you are talking about. Wrasses etc seldom AFAIK) go deeper than 5-6 cm. Things like sand[prawns impact far deeper into the sands - up to 1 to 1.5m - by their burrowing. Wrasses etc will thus have little impact on the anoxic layers in the DSB provided that it is deep enough, whereas burrowing animals such as the sandprawn will definitely impact on the DSB.
     
  20. crispin

    crispin Thread Starter

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    am i correct in understanding when i think that LR covering a DSB for 80% of the flat area would be pointless as the flow is restricted and thus the area under the LR is anerobic. Its better to scape the LR over 40% of the area in a more verticle arrangment, thus creating habitat and hidey holes as getting an active water flow around the LR and leaving more of the surface of a DSB to be oxygen rich?

    The point about particle size makes lots of sence.

    If DSB are not normally run in a tank and external in the sump area and people seem to dislike the look of a "bare bottom"----(in a tank that is!) then am i correct in thinking its no9rmally a Shallow sand bed of 5-8cm in tank and the Deep run externally?
     
  21. Warr7207

    Warr7207

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    Majority run this sort of setup, maybe we need a poll to find out ?
     
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