How do u know DSB is working?

Discussion in 'Biological/Natural Filtration and Deep Sand Beds' started by RiaanP, 12 Jan 2009.

  1. RiaanP

    RiaanP Moderator

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    My DSB is fairly new. 2.5 months. Seeded from pieces of live rock from another tank and that tank sump.
    Question, how do I know it is working. I noticed some small bubbles on the sand surface. Is that a good sign?
    dimension 38*32*15
     
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  3. jacquesb

    jacquesb Retired Moderator

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    Yes Riaan - this is indeed one way of seeing that the DSB is working. Those bubbles are either nitrogen, or oxygen (the building blocks of nitrates).
    Another way to see the DSB is "working" is that your nitrate levels are nearly always close to 0 (very low).....
     
  4. RiaanP

    RiaanP Thread Starter Moderator

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    OK, good,
    but my water params are
    KH 11
    PH 8.5
    NO2 0.0
    NO3 >100
    NH4 0
    PO4 between 2 and 4

    The PO4 definitly came down since last time I checked all stuff in December.
     
  5. jacquesb

    jacquesb Retired Moderator

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    Well - as in your own words "starting to work".....

    Give it time - after a while the DSB WILL reduce your nitrates. Just a quick question though: how much are your feeding? It is indeed still possible that your nitrates are staying high, because you are overfeeding....

    Overfeeding is a relatively common practice - whether reefers do it explicitly, or not on purpose (un-knowingly).....
     
  6. RiaanP

    RiaanP Thread Starter Moderator

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    I think I might be overfeeding.
    Morning some flakes, normally all gone within 3 to 5 minutes.
    Late afternoon I give some bloodworms, small block. Also eaten quickly.
    how do I know when I overfeed visually?
     
  7. jacquesb

    jacquesb Retired Moderator

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    You won't know - until it is far too late..... overgrowing nuisance algae....

    You don't need to feed THAT much. Only a very small amount, once a day. Unless you explicitly want to overfeed.

    With the 2 x TS2's in my tank's sump, and feeding very little, all my fish was still as fat as pigs.... BUT, my soft-corals would not grow. My nitrates was at 0 with my DSB running (even before I had the 2 x TS2's).....
    I started overfeeding on advice from another reefer - and then all of a sudden my soft-corals started growing like CRAZY!
    BUT - my nitrate levels are now around 20ppm.....
     
  8. sunburst

    sunburst

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    IMO Overfeeding is relative. Rather.. Healthy feeding....recognising what your system can digest and deal with. DSB are very limited in the speed that Nitrates are consumed. A steady increase in Nitrates is the canary in the coal mine. Cut the bio load, or improve filtration. You could also have a dsb that is malfunctioning .... ie not enough flow, fall out areas or dead spots where detritus gathers, to much clutter suffocating the sand water interface

    If you do wish to push the bio load envelope do so slowly. Some of our old salty dog members with DSB's have done so successfully.
     
  9. Tobes

    Tobes Retired Moderator

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    2.5 months is still very young for a DSB to function to its full capacity. Sometimes it takes 6 months and longer to mature properly.
     
  10. sunburst

    sunburst

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    Thanks Tobes. 6 months agreed. But even after 6 months cyano and diatom blooms will still be frequent. I missed the two months bit
     
  11. Tobes

    Tobes Retired Moderator

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    Also rake the top layer of the sand occasionaly (about 10-20mm) to prevent detritis from settling and help with aeration. Alternatively you can get a couple snails to do it. don't go deeper than that, otherwise you might disturb the anarobic activity and compromise the natural nitrate reduction (NNR).
     
  12. sihaya

    sihaya

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    I wouldn't "rake" the sand at all... instead, use a turkey baster or a small powerhead to "blow" the top layer around some. It's a gentler way of doing the same thing.

    Yes, bubbles are a good sign.

    Also, if you want to really see what's going on down there, get your hands on a microscope and look at a pinch of the sand under it... if your sand bed is healthy, you'll see a whole other world in there!
     
  13. Reef Maniac

    Reef Maniac MASA Contributor

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    Very good advice - most of the sand-living organisms are very fragile, and the sand grains can actually cut or crush them if the sand is moved forcibly. Also, many of the sand-living worms actually build tubes by "gluing" the sand granules together - if the sand is disturbed at all the tubes will bread, leaving the worms exposed to predators, etc.

    See it this way: the detritus that has fallen to the floor of the sand bed is being eaten by the little critters - why do you want to suspend this in the water column again, where it will be pumped back to the display tank???

    WOW, that NO3 and PO4 values are VERY high, and will certainly not be good for your corals. With the dsb being 2.5 months old, I would suggest that it has not fully matured yet, and that your bio-load should be kept very light at the moment. Use GFO phosphate remover and grow whatever macro algae you can find in the sump, to try and reduce these two parameters. Are you not perhaps using an aerobic filter (fluidised sand filter, canister filter, trickle filter, under-gravel filter, etc.) in your system? If so, that will explain the high NO3 level.

    Hennie
     
  14. crispin

    crispin

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    hennie, wont you expand on the section in blue for me, or shiya or sunburst or anyone:) i dont quite equate why an aerobic filter would increase the NO3 levels, although i dare say its pretty logical, i'm just missing the point.
     
  15. Reef Maniac

    Reef Maniac MASA Contributor

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    Sure - aerobic filtration can only reduce ammonia to nitrite to nitrate. You need an anaerobic condition (i.e. low oxygen levels, but not completely absent...) for the reaction to continue, where the anaerobic bacteria uses nitrate and produces nitrogen gas (the last stage of the nitrogen cycle...).

    Where an aerobic filter is too efficient, such as a fluidized sand filter, the nitrate is either produced quicker than what the anaerobic filtration in the live rock / deep live sand bed can handle, or the nitrate is dissolved in the water column, and only a small amount of this reaches the anaerobic regions in the LR / DLSB - either way, the result is a nett increase in nitrate, and an (ultimate) increase in nuisance algae.

    I hope this makes sense - shout if you want me to elaborate.

    Hennie
     
  16. crispin

    crispin

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    and similarly if you have to rapid flow over a dsb it doesnt penetrate into the anerobic layers, or is carried away before the anerobic bacteria can process it further, basically defeating the object?
     
  17. RiaanP

    RiaanP Thread Starter Moderator

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    I got a DSB in sump and a TS2 skimmer.
    Tank got a 2cm layar crushed coral rice crispis or finer.
    Got cheato and caulerpa in yhe sump. They grow like mad... Cheato ball doubled in size within 3 weeks. And the caulerpa is in separate water plant pot to keep it separate. As long as it grows I will the PO4 is high I will leave it it there. I see that the PO4 test looks slighty lighter. not that port wine color but more sweet red.

    I installed a scrubber yesterday. 50cm wide by 35 high. Hopefully this will make a difference.

    Flow over DSB is not hectic at all. Maybe not matured enough.

    Riaan
     
  18. Reef Maniac

    Reef Maniac MASA Contributor

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    That's where your problem is - this layer is MUCH too shallow to develop an anaerobic zone (especially with your course sand...), and you thus don't have the nitrate processing capacity of a deep live sand bed.

    Hennie
     
  19. crispin

    crispin

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    i think he has a shallow bed in tank and a deep sand bed in sump
     
  20. RiaanP

    RiaanP Thread Starter Moderator

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    Yip, deep in sump, shallow in tank. With a golden head Goby that keeps the DT turned over.
     
  21. RiaanP

    RiaanP Thread Starter Moderator

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    Pic of sump. Well before cheato was added.
    [​IMG]
     
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