How achievable is a Nitrate environment?

Discussion in 'Water Chemistry' started by scoobiemandan, 29 Sep 2019.

  1. scoobiemandan

    scoobiemandan Member

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    As the title suggests; How achievable is a Nitrate free environment.

    Say, for instance, you have Nitrate removing equipment to provide the tank with Nitrate free water at water changes but you are dosing ferts for your plants. Add these Nitrogenous compounds to those from organic matter in the tank breaking down, what are the tools available to use up these compounds to have a 'complete' Nitrogen cycle in the tank?

    I'm asking as I'm trying to get an insight into how easy or difficult is is to achieve? Whether it can be done on a budget or whether it's a costly task?
     
  2. tam

    tam Member

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    If you have the the right balance of plants to use up the ammonia before it's converted to nitrate, and you only add in as much additional nitrate via ferts as your plants use up (or don't add any and just provide everything else they need to uptake the ammonia)... then you could do it. Most people just accept some as normal though cos finding the balance is tough and doesn't always make a nice looking tank.
     
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  3. dw1305

    dw1305 Expert

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    Hi all,
    As @tam says by far the easiest way to achieve a low nitrate environment is to have plenty of plants, including some with the <"aerial advantage">. If you have a lot of plant growth you won't ever have much build up of NO3-, the plants will convert it into more plant. When you remove the plant material, you export the nitrogen (N). You won't ever get to an NO3 free environment, but I don't see any advantage in having "no NO3" over having "some NO3".

    The Leaf Colour Chart (LCC) is really useful as a measure of nitrogen content, put simply the plants don't lie. I'm not sure how much NO3- I have in my tanks, but if the conductivity reading is 120 microS., and the <"Amazon Frogbit rosettes are a mid green"> I'm good. One reason I know I don't have much NO3, is because I don't have many ions of any description.

    [​IMG]
    If you decided you did want a nitrate free environment there are ways of achieving it. It is possible using an <"anion selective resin"> to polish the water after initial treament.
    It is a costly option, we tried scientific grade <"amberlite resins">, when we used to work on waste water, but they fouled really quickly. This the <"blurb for them">. You would have to measure NO3 levels to tell you when the resins needed re-generating, or whether the plenum etc. is working. @alto would be the best person to advice you on the <"best test kits">.
    You can use <"denitrification coils, or a Berlin or Jaubert plenum>, to complete the denitrification arc.

    Sellers of Matrix, Biohome etc. will tell you that you can have <"simultaneous aerobic nitrification and anaerobic denitrification"> in the same media, with a steep oxygen gradient across a small spatial separation. There are a number of reasons why this isn't a good idea, the primary one would be that you are always teetering on the brink of low oxygen levels, leading to incomplete nitrification, which leads to <"ammonia and/or nitrite levels rising and killing all your fish">.

    It is pretty likely that you will get some anaerobic denitrification in the substrate, even if you don't have a plenum or <"biocenosis bucket.">.

    By far the easiest way to achieve a low nitrate environment is to have both
    • a substrate and
    • plenty of plants.
    cheers Darrel
     
    Last edited: 29 Sep 2019
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  4. jaypeecee

    jaypeecee Member

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    Hi Darrel,

    Do the numbers under each of the LCC colours refer to N or NO3 ppm? Also, if your conductivity is as low as 120 microS/cm, your GH and KH must be very low. I would estimate that each is less than 2dH. What fish do you keep, if you don't mind my asking?

    JPC
     
  5. dw1305

    dw1305 Expert

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    Hi all,
    I'd need to go back to the original paper to find out what nitrogen levels 1- 6 relate to, but the numbers aren't either nitrogen (N) or nitrate (NO3). <"The idea"> is the same one as the Duckweed Index, you don't need to measure the amount of nutrients you just put the leaf on the chart and it tells you whether you have enough nitrogen, or you need to add a bit more.
    They would be quite low, it is rain-water, but most of the dissolved solutes are still calcium (Ca++) and (bi)carbonate (HCO3-) from atmospheric dust.

    There isn't anything magical about 120 microS, it was just near the middle point of the 90 - 150 microS range that I'd found allowed some plant growth with soft water.
    Mainly S. American ones, Apistogramma, Corydoras, Otocinclus, Hypancistrus, Pencilfish etc. I've kept away from any extreme black-water fish, because our rain-water is still too hard for them to breed successfully, although for maintenance it is fine.

    If I measure the pH during the photoperiod it will be ~pH8, but all my snails show shell erosion so it is getting below pH7 at night.

    I've kept fish for a long time and I've always used rain-water, originally I had no idea about water chemistry, but some-one told me it was the best thing to use, and I've never found a reason not to use it.

    I saw <"Nick Ridout"> recently, and he told me that I was the person who originally put him on to using rain-water, although I don't remember this.

    cheers Darrel
     
  6. jaypeecee

    jaypeecee Member

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    Hi Darrel,

    Straight rainwater - quite something. I suspect the snail shell erosion is the result of acidic water at night in conjunction with very low calcium in the water. Do you supplement their diet with cuttlefish bone? As your KH is very low, do you never get pH crashes? Presumably, you add ferts to the water so is the 120 microS/cm figure before or after adding ferts?

    JPC
     
  7. dw1305

    dw1305 Expert

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    Hi all,
    I don't add a calcium carbonate source to the tank, but I put in <"green vegetables"> for the fish, snails, Asellus etc.

    Snails can use a dietary calcium source to build there shell at the mantle, but they <"can't repair the older shell">.
    Not as far as I know. When people get very low pH and dead fish they are both really symptoms that has something has gone wrong, rather than the low pH having directly killed the fish.

    Objectively you can't really get pH crashes in very soft water, just because pH is inherently unstable and can fluctuate from pH6 to pH10 during a diurnal cycle. This is what happens in the natural environment as well. Have a look at the Diana Walstad's "Star Lake" quote, and the Rocha et al. figures, in <"TDS and remineralising....."> for more details.

    What has really helped me is to think about changes in water chemistry, rather than just changes in pH.
    • In soft water small changes in water chemistry cause large changes in pH and
    • in hard water large changes in water chemistry cause small changes in pH.
    The conductivity will be higher after the fertiliser addition, but will drop down again towards the datum range as I change water.

    I don't regularly measure the conductivity any more, I did for a few years, but now I have a good idea of when I need to add some tap (in the winter), or RO (in the summer), water. Our tap water is "very hard" from a deep limestone aquifer, it is very low in nutrients, so it really just adds hardness (both dGH & dKH).

    These are the current figures from Wessex Water for "Zone 41 Fiveways", calcium carbonate = 328 mg/L, NO3 = 8 mg/L and conductivity 630 microS.

    cheers Darrel
     
  8. Soilwork

    Soilwork Member

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    Of course I know better than to trust a hobby grade test kit but I do run lean on both no3 and po4. My water is soft and I don’t change it at all.

    I feed a good amount of an insect based flaked food twice daily and use an deconstructed sponge filter to create good surface agitation via an air pump for consistent gas transfer at the surface. I figured id need ample and stable oxygen levels to ensure nitrification 24/7 as to keep these nutrients as low as possible.

    My thoughts are that because these parameters are so low (often undetectable) in many natural environments where our livestock exist, I’d want to keep my planted tank the same.

    I top up now and then with RO or rainwater and have a steadily and very slowly declining TDS value of around 240ppm.

    Most of my plants are doing fine except the Hygrophila carymbosa who's leaves are pale as in Darrel’s reference chart. I’m not too bothered about this. This plant is a menace in high tech setups and is clearly being outcompeted. 780C7E6C-3718-4579-9B08-FE862B438157.jpeg 11D7D2D4-829B-4F7A-8A3F-DE5A239CFD82.jpeg 11D7D2D4-829B-4F7A-8A3F-DE5A239CFD82.jpeg

    Most of my plants are deep rooted and just continue to grow and grow despite no fertiliser dosing (unless you count fish food) or additional co2 other than what is provided via surface mixing. Lights are on for about 12 hours a day.
     
  9. Edvet

    Edvet Global Moderator Staff Member

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    Either there are little to no plants or there is constant replenishing in nature.
     
  10. Soilwork

    Soilwork Member

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    can you explain in a little more detail what you mean?

    Thanks

    CJ
     
  11. Edvet

    Edvet Global Moderator Staff Member

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    In most aquatic environments with low nutrients there are few/litle plants, just fallen leaves, fallen branches and substrate. In cases where there are plants there has to be a source of nitrogen and in cases of low levels a constant replenishing through flow patterns has to be considered (all nutrients used are replenished through the flowing of the stream, creek, river)
     
  12. Soilwork

    Soilwork Member

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    I hear this a lot. In my tank there is always a source of nitrogen and phosphates to a degree because they are being produced continuously via the nitrogen cycle and fish, even if they are low. Just like in nature.

    You could argue that the simple act of feeding fish adds more nutrients because the density is higher than in nature. Now obviously the demand for these nutrients in my system exceeds supply, otherwise I would have an accumulation. How can one system
    Generate so much plant mass with such little to work with?

    On a final note, you would probably have a hard time measuring no3 and phosphates in a pond too, that has little to no flowing water.

    regards

    CJ
     
  13. Edvet

    Edvet Global Moderator Staff Member

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    Feeding the plants with fishwaste only should be no problem, just make sure you adjust lighting levels accordingly.
     
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