Reducing nitrates

Discussion in 'General Aquatic Talk' started by Laure, May 22, 2009.

  1. Laure
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    Laure Algae harvester

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    Hi

    I just recently read this interesting article. It is about using vodka to reduce nitrates in the tank. It also cites other references.

    http://reefkeeping.com/issues/2008-08/nftt/index.php

    I don't know if it can be applied to freshwater planted tanks. It then made me think about the fact that report reduced algae when dosing carbon additives such as Excel or EasyCarbo. Could this be because these contribute to reducing NO3 and PO4? We know excess levels of these nutrients contribute to algae...
     
  2. Dirk B
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    Dirk B Aquascaper

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    Hi Laure,

    This article shifts the emphasis to the use of ethanol/vodka in reducing nitrate, but the process that is being described here is actually anaerobic filtration. Anaerobic bacteria, or as the name actually indicates, bacteria that do not use oxygen in order to obtain energy (they also do not want to have any oxygen in their environment or else they are overgrown by those requiring oxygen). These bacteria are very happy to use nitrate (NO4-) and to convert this to nitrogen gas and thereby they actually get rid of the nitrate. You need to run a filter in your system on a branch off your biological filter and you need to run this very slowly so that you do not introduce a lot of oxygen in the process. These bacteria then do you the favor of converting nitrate to nitrogen gas whereby this means that you do not need to do water changes. For this reason, the marine fish keepers are very interested in this and also the discus keepers. I use such a system on my recirculating discus setup. These bacteria grow better if they are supplied a carbon source such as ethanol or vodka. I do not use this but my filter helps tremendously in keeping nitrate levels lower without having to do big and ongoing water changes.

    Kind regards,

    Dirk
     
  3. Laure
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    Laure Algae harvester

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    Hi Prof

    Thanks for the clarification. I know the marine guys use something called a deep sand bed (DSB) in their sumps to grow the anaerobic bacteria. What method/filter material do you use in your setup? How long does it take before this anaerobic bacteria population starts to grow and is there anything one can do to check other than testing for nitrates and over time seeing a reduction in the levels?

    Also, I've read of people claiming that they have anaerobic bacteria under large rocks in their tanks. These are obviously the areas with little water flow through the substrate. It has also been reported that moving such a rock will release these bacteria in the water column where they will die and cause big problems in the tank. I'd like to know a little more about this is somebody has the time to explain...
     
  4. neilh
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    neilh Algae harvester

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    Dirk, I gather you are using a low flow denitrator. Had any experience using a Sulphur Denitrator that is so popular in the marine fishkeeping side?
     
  5. Dirk B
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    Dirk B Aquascaper

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    Hi Laure and Neilh,

    I use course gravel in one of the canisters and Siporax in the other. I am not sure how long these bacteria take to establish, but it is not as fast as normal bacteria in an aerobic biological filter. At a guess I would say 4 weeks minimum, I can do some checking in my literature though. Other than checking for nitrates there is effectively nothing else that you can do, no.

    I can believe that people claim that they have anaerobic bacteria under rocks. There is also an old argument that if you have filter media such as Siporax in a normal filter that the deeper crevices will hold the anaerobic bacteria whilst those areas in which the water and thereby oxygen circulates better, will harbor aerobic bacteria. I think that as soon as oxygen is in the environment, the anaerobic bacteria are out-competed by the aerobic ones and they dissappear. I also do not believe that the release of these bacteria can do any harm.

    Neilh,

    Yes, my system is a low flow denitrator. I have no experience using a sulphur denitrator no. Perhaps you can explain.

    I will also check on some literature that I have on Siporax where the process is explained very nicely.

    Kind regards,

    Dirk
     
  6. neilh
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    neilh Algae harvester

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    Let me see what I can find. From what I remember the sulphur ones rely on a chemical reaction rather than the bacteria consuming the Nitrates
     
  7. neilh
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    neilh Algae harvester

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  8. Dirk B
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    Dirk B Aquascaper

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    Hi Neilh,

    My very heavy virus checker informs me that that link has a Trojan virus attached so I cannot read it!

    Kind regards,

    Dirk
     
  9. neilh
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    neilh Algae harvester

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  10. cory
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    cory Noob

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  11. butcherman
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    butcherman Noob

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    Did anyone make a denitrator like thione cory was talking about? i heard that a denitrator very difficult to use and you also need to constantly feed it? and some ppl reported that it could leak poisonous substances back into the tank?
     
  12. wearsbunnyslippers
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    wearsbunnyslippers Administrator Staff Member

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    if you have enough plants in your tank you will not need a denitrator. in fact you will need to add some nitrates back to your tank, as the plants will be using them up faster than they are produced...
     

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