Visser's undergravel denitrator

Discussion in 'Biological/Natural Filtration and Deep Sand Beds' started by Visser, 30 May 2012.

  1. Visser

    Visser MASA Contributor

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    Yep, the name says it all.

    I have been holding out a bit on an idea i've been testing for the past year & 3 months.
    I call it the Undergravel denitrator .

    I know that undergravel filters have been a touchy subject in the past. I think most of this has got to do with the fact that it has been wrongly utilized due to the fact that in most cases, the flow that has been forced through these substrates was done too quickly, & therefore never permitted anaerobic bacteria to form (and also had the ability to form high levels of nitrates due to the organic matter that got trapped inside).

    Ok, i will make this sweet & simple. (& the idea is free for anyone to use if they want...)

    VISSER'S UNDERGRAVEL DENITRATOR

    Introduction:
    I have in the past tried numerous methods of facilitating a working denitrator in my many fish tanks, but never could i find one that is truly reliable.

    Firstly, i tried building a coil denitrator unit - This was probably the most difficult method ive ever tried. I was always getting either higher nitrates out than what went in, or got only a bad sulfurous smelling slow dripping unit. (so i decided to carry on)

    Next i tried the sulphur denitrator - this unit worked quite well, up to the point where its pump got stuck without me realizing it, & then suddenly restarted a couple days later only to find my whole tank poisoned by the decomposing bacteria.

    I then employed a DSB (deep sand bed) which turned out to be a very stable denitrating method, but i could never quite get that beloved 0 ppm nitrate number.

    This got me to the point where i started researching other means of removing nitrates from my aquariums water, & that is where the undergravel denitrator was born.

    Please note: All ideas utilized in this method is my own, & as far as my knowledge & research goes, there is no similar method used. (please let me know if you've seen any similar ideas)

    Explanation:

    Firstly, here is a drawing of the basic idea of how it works:

    [​IMG]

    The idea was originally to use a DSB small enough to fit in any size sump, but still get the full capabilities of a much larger DSB.

    In the drawing you can see the typical layout of a DSB with water running over the sand bed & normally a sand stirring crew to "turn" the aerobic part of the DSB.
    The difference in this method is, that it doesn't require the water to travel into the DSB, & then back up (which takes quite a long time by the way).
    This unit only requires the water to travel one direction into the DSB.

    Under the DSB, i installed a normal under gravel filter (the type that you can purchase from any petshop over the world probably). Next, drill a small hole on one of the corners on the side closest to the overflow side. This is where i installed the airline tubing that runs from underneath the DBS to the surface. (make sure to use a long enough tube)

    Next, i place a piece of filter wood (that i cut to fit very snug on top of the undergravel filter) to prevent the DSB substrate to fall into the cavity.

    Now place the undergravel filter onto the DSB compartment, & fill up with your favourite DSB substrate. (i found that for this method, it is better to use a medium sized sand to help water flow through the entire area of DSB)
    Make sure the airline tubing's end is out of the sand...

    The depth of the sand is very important since it is going to use a bit more "depth" of sand before the anaerobic bacteria is going to form.
    I used in mine, a depth of 150mm - 200mm on top of the filter pad.

    The startup
    Now that everything is installed, the next thing to do is to start it up.
    The easiest way to do this is to slowly pour water onto the DSB until water is at the overflow level.
    Now, start up the pumps & let the water run over the DSB & into the return pump chamber.
    To get the position of the airline tubing in place, i bought the airline suction cups, clipped it around the tubing & stuck it to the glass.

    Next step to take is to get the siphon to run, so, simply suck on the end of the tube until the water is through, & quickly lower the end down (lower than the level of the DSB compartment's water).
    This will make the water run through the tube @ full blast.
    Next, clip the tubing to the suction cup, & slowly push it higher until you get a slow dripping flow. (about 1 drip per second).

    & there you have it folks, the most reliable denitrator i have ever seen.

    But as they say, the proof is in the pudding, so...

    Test results
    I have used this method in 3 different systems (2 of my own, & one for a friend) with almost exactly the same results each time.

    To help start the working of the DSB quicker, i injected bacterial additives into the DSB with a syringe. (seachem stability & brightwell microbacter)

    I allowed the drip to continue at a rate of 1drip/second in all 3 systems.
    Nitrate & nitrite tests were done every day to compile results (for first 3 weeks, thereafter every couple days).

    Results as follows: (tests with salifert test kits, some test results left out where the same as previous days)

    Day1: nitrate in tank: 10ppm Denitrator: 10ppm
    Day2 10ppm 10ppm
    Day5 12ppm 15ppm
    Day8 16ppm 30ppm
    Day10 16ppm 10ppm
    Day18 12ppm 2ppm
    Day20 12ppm 0,5ppm
    Day23 8ppm 0,1ppm (first day of 0 nitrates from outlet)
    Day30 6ppm 0,1ppm
    Day35 5ppm 0,1ppm
    Day49 2ppm 0,1ppm
    Day60 0,2ppm 0,1ppm
    Day70 Undetectable 0,1ppm
    Day90 Undetectable Undetectable

    (& Just to clarify, there may also have been other denitrating factors like skimmers & LR, but according to my knowledge, they would not have been able to decrease nitrates so quickly)

    Explanation
    Well, all i can say is that is works really well!!! There are a lot of other posts about the workings of a DSB, so i wont go into that right now, but i just employed a method of producing more "denitrated" water from the same sized DSB than before which means that nitrate levels will automatically be kept lower in the tank & eventually be undetectable.

    Since i started using this method, my tank has been almost 100% algae free (and amazingly phosphate free as well.)

    Will post some photos of it soon to show how its working in action.
     
    Keanan, shaunn and pXius like this.
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  3. Visser

    Visser Thread Starter MASA Contributor

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    Oh yeah, & thanks for viewing the thread, & please post comments/criticism/ideas.
    All is appreciated.
    Looking forward to hear what you guys have to say about this idea!!!:thumbup:

    & i will see you all at the AquariumExpo2012!!!!!
     
  4. belindamotion

    belindamotion Google Master

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    I've just started reading up on the Undergravel Filters again as I'm thinking of adding one to my Tank upgrade...reverse UGF, as an ADDITIONAL Filter, so I'm very rusty in the knowledge department and have to learn all over again...:blush:..I was thinking of using "180 Micron Plastic Mesh" as a cover...to prevent substrate from falling thru...would that not be better than the Filter Pads...?
     
  5. Brent

    Brent

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    I'n going to tag along for the comments on this one...
    sound like a good idea.... Well done
     
  6. EFJ

    EFJ MASA Contributor

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    Sounds like a nice idea. Will stick around for further info. Just one question, over time wouldn't the tube get blocked up and if so how would you clean it? Maybe you should use a long plastic tube as a sleeve for your rubber tube to slide in for cases where you might have to remove the pipe for cleaning. Keep up the good work:peroni::thumbup:
     
  7. JDV

    JDV

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    tagging
     
  8. pXius

    pXius

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    Also, you said filter wood, Did you mean filter wool?

    I'm also concerned about the pipe blocking.

    What the system volume this was used on?

    Great job, this is really awesome!
     
    Last edited: 31 May 2012
  9. Ivyalt

    Ivyalt

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  10. mariusmeyer

    mariusmeyer

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    If I am not mistaken this is called a plenum. You modified it nicely to get the nitrate reduced water out of it.
     
    Last edited: 31 May 2012
  11. brentv

    brentv

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    This system has been used before Christiaan,
    I have a mate in Germany, Micheal that ran a system of a slow drip out U.G filter with a DSB, think it is called the 'Berlin System'
    Maybe google that?
    In priciple the idea seems great but how would you get access if this inline pipe does clog without stirring up your whole filter bed?
    As it flows slowly through the sand etc it will work very well but if it does clog that specific bacteria and living organisms in a certain part of the bed might get starved of a nutrient etc and cause a whole pile of other problems!
    I'm not a pesimist, but if you could get a sure fire method of making sure this could never happen you could be in business!!.;)
     
  12. shaunn

    shaunn

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    this post was just @ the right time i am just about to add a dsb to my system and i am gona use ur method with my dsb thx fro the gr8 thread a rep point for u
     
  13. mariusmeyer

    mariusmeyer

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    This is not a specific method but rather a mix of components used in different traditionally used methods.

    The plenum first got introduced in the Jaubert Method which did not make use of an overflow system such as the berlin method.
     
  14. Visser

    Visser Thread Starter MASA Contributor

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    Thanks for the replies guys:
    Firstly, there is absolutely nothing that could clog the pipe as the water get filtered by the sand. Ive had the first test running for +- 6 months without any clogging.
    I did install a backup pipe on the first system that i only blocked off in the case the other pipe gets blocked, but never had to use it!

    The only thing that could retard the drip, is when nitrogen gas builds up underneath the "plenum" , but it just takes a day or 2 to take all the nitrogen bubbles out, & then everything runs fine again.

    Thanks @brentv, you wouldnt perhaps have a place where i can contact your friend from germany, would love to talk to him about his system & how he operates it!!!
    The only answer i can give you regarding a backup to keep the flow going in the case of a blockage is to install a backup line on one of the other corners & just block it off untill needed.

    As for the filter wood, lol, yes, its actually filter wool (typo). I used the standard white filter pads that you can buy in sheets @ any pet store.
    I wouldnt use any filter plastics, as the sand grains would very easily clog the filter & not allow any water through, & you need something to create some cavity between the sand & the undergravel filter to allow easier flow of water.

    Hope this answers some of the questions, please ask & comment as much as you can, i would like to set up a pros & cons list for this method to see if the advantages outweigh the disadvantages.
    Thanks again for the replies guys!!!
     
    Last edited by a moderator: 26 Nov 2015
  15. Visser

    Visser Thread Starter MASA Contributor

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    Thanks @shaunn, It would be excelent if you could also start this denitrator to see that you get the same results. Could you perhaps also keep log of your nitrate levels that you tested if your going to implement it. Would greatly help to compare statistics for seperate systems. Please send me a pm with your number, will sponsor you the nitrate tests if your willing to keep log of your nitrate levels!!! Lol
     
    Last edited by a moderator: 26 Nov 2015
  16. pXius

    pXius

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    Sweet, I'm actually building a new sump this weekend and I'm very interested in this. Do you run this on your cube in your aquarium specs?

    My system volume is much larger so I'll be running a bigger DSB. Maybe I'll run 2 lines instead of one?
     
  17. shaunn

    shaunn

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    what are the implication of not having the siphon running ? @Visser my sump is bit diffient than ur sump as i don't have diffient water levels in my sump ?
     
    Last edited by a moderator: 26 Nov 2015
  18. brentv

    brentv

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    Hi Christiaan,
    Will PM you Mike's no, good luck with this;)
     
  19. Visser

    Visser Thread Starter MASA Contributor

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    Hi @pXius, im am currently running it on my 150l cube nano, but ran the first one on a 370l hexagon aquarium.

    I wouldnt suggest running it it with two lines. Rather use 1 line, but just lower the tip of the line to give more flow.

    You can work out the flow running through the airline by simply timing the volume / minute, & then adjust the flow so you get the full tanks volume circulated in approx 50-60 days. This will give you a good starting point.

    If you really want to have 2 lines running, i would suggest splitting your DSB compartment with a glass divider, & use 2 separate ones running at the same time.

    As for the size of the DSB. The one im running at the moment for the 150l cube is 200x300x200mm deep. So as you can see, its relatively small compared to the conventional DSB. This one has only been running 4 weeks, & im already reading 0,5 nitrates from the outlet.

    The reason for getting such quick results in this one is that i inject bacteria with a syringe into the DSB, & also dose +-1ml vodka for the first couple weeks to help the bacteria a bit.
     
    Last edited by a moderator: 26 Nov 2015
  20. Visser

    Visser Thread Starter MASA Contributor

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    Hi @shaunn, can you please upload/email me a picture of your sump. Might be able to help you to get it running in another way.

    You literally only need a water level of 10mm lower than the level of water over the DSB to get it to drip. Its that easy!
     
    Last edited by a moderator: 26 Nov 2015
  21. shaunn

    shaunn

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    [​IMG]

    note that the the middle paine the water is flowing over has been removed that's were my dsb is going to go
     
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