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Thread: Another dang Newbie asking about nitrate...

  1. #1
    Join Date
    Jul 2009

    Another dang Newbie asking about nitrate...

    Greetings, all!

    I am the planing stages of what I hope will be a successful pond; I have been doing quite a bit of preparatory research on ponds over the last few months, and I have reading quite a bit on the various Koi-related forums. I would like to dig for some greater insights as to the current wisdom regarding and methods by which ponders are managing nitrate.

    The *textbook* story of which I am most familiar is that nitrate is produced as a by-product from the metabolism of ammonia (NH3) by aerobic-operating bacteria: NH3 --> NO2- --> NO3- (nitrate). This is consistent with my experiences from aquarium keeping, and I believe I am correctly refering to this pathway as "nitrification."

    Although nitrate is far less toxic than ammonia (or the intervening nitrite), we still do not want nitrate in our ponds -- or at least, we do not want very much of it around. So how to get rid of it / manage the nitrate concentration? Through my reading, I have only come up with a couple of methods, although possibly I am missing some other possibilities?

    1. Bakki shower. I found a nice technical paper on this from the waste-water treatment industry; this paper referred to the process as "ammonia stripping." Makes sense, but costs electricity to raise the water up to the top of the shower, and increases the evaporation rate of the pond.

    2. Water changes. Obvious.

    3. Attempts at incorporating denitrification processes. This is very intriguing to me, but the idea does not seem fully developed/widely used even among the marine aquarium folks, and I have found little mention of denitrification methods in pond circles. Some examples I am aware of are Hozelock's "Trinamic" filter, which presumably encourages the growth of some denitrifiers in the bio-media, and Kevin Novak's "anoxic filtration" concept. I have no basis of experience that either the "Trinamic" filter or Kevin Novak's system are functional at truly rendering nitrate, but I can relate to the advantage -- at least in theory -- of being able to get rid of nitrate from the water via biological means.

    I am digging into this denitrification idea a bit heavily because I reside in San Diego County. In this part of the country, we have a rather expensive "tiered" electricity pricing, which means that running a couple of pumps to push water to the top of Bakki showers can get really expensive. The arid environment here lends itself towards a fairly high evaporation rate, which is another vote against the Bakki. Water itself is an increasingly expensive commodity as well; currently, we are under some restrictions as to water use, and all-out water rationing is a possibility for us in the future. That means that a lot of water changes could become problematic.

    All of this is not to imply that I do not expect to make water changes, or that would never consider some sort of shower filter, but I would really like to have some other tricks up my sleeve for dealing with nitrate, if (and probably "when") I need to control/reduce nitrate levels in my pond. I don't want to hate my pond every time I get a bill from a utility company.

    I am actively looking for any ideas or insights into the control of nitrates, be they mechanical (Bakki), biological (denitrification), or by some other means I haven't considered.

    Thanks for any thoughts,


  2. #2
    Daihonmei MikeM's Avatar
    Join Date
    Dec 2003
    Orlando, Florida
    I think you've summed it up pretty well. Some think the Bacteria House media provides some denitrification, but it would be nominal in the context of a pond.

    I agree that nitrate is undesirable. The lower the better. I would suggest, however, that the nitrate is also an alternate measure for the presence of contaminants of all sorts, including hormones, metabolites, etc. We do not have test kits readily available to identify eveything that contaminates water in the koi pond. Water changes address everything, assuming your source water is acceptable.

    Water begins to deteriorate the moment it is added to the pond. In the pond context, we pretty much have to rely on dilution being the solution for the pollution.
    Last edited by MikeM; 07-29-2009 at 05:56 PM. Reason: typo

  3. #3
    Join Date
    Sep 2006
    Hey Paul, welcome. I have to complement you in that you seem to be going about things logically - which NONE of us did in the beginning! LOLs

    NitrAte , as you have identified and explained, is an inevitable final byproduct of a closed system where biological activity occurs. And we tend to then see our challenge as stopping nitrAte from building in a close system like a koi pond. But things are not only building in a closed body of water occupied by living things- other 'things' are being lost by that very same activity. In that case we are talking about micro nutrient and buffering capacity and so the ion composition of virgin water.

    In a separate thought--- you have the train of conversion absolutely right. But the devil is in the details! How much is in each 'car' of that train? If we consider that the ammonia produced in your pond has a factor of 10 and each time you convert, you convert from 10 ammonia to 10 nitrite to 10 nitrate, then nitrate will pile up based on dilution ( size or gallonage of your pond). Assuming you want to stock you pond well, we can't really reduce the front end factor of 10 for the ammonia. But ammonia in a koi pond is not only produced from the gills of the koi. Some comes from the break down of organic material very present in an outdoor pond. So maybe you koi only produce 7 in ammonia and 3 is produced by organic decay.
    In this case, an excellent design, lots of aeration, sump dumps go a long way to reducing your ammonia factor to 7 to begin with.
    Now lets talk about creating a leaky system- not a pond that leaks water but a system that leaks nitrogen waste gases and intermediates of ammonia/nitrite and nitrate. Towers are good for this, as is evaporation and the addition of a 'second pond surface' area as the one created when you run water over media in a trickle tower. Add a foam fractionator and you assault the conversion model at the front end even further. This all lightens the load and weight of the 'cars' on your conversion train making the end product nitrAte a smaller value.

    Now back to the first point-- the very best way to dilute the end product of the conversion train is the simple water change. So why is this primitive and non-sexy technique so good? Well it will not only take out the excess build up of nitrogen via dilution, but it will also restore those things lost in the water due to biological activity. And if you do water changes in small amounts but with frequency, you are also impacting the conversion front end once again ( dilution of organic fines) while keeping the back end ( NitrAte) close to an ideal base line reading. It's all good!

    - JR

  4. #4
    Daihonmei PapaBear's Avatar
    Join Date
    Oct 2005
    Davenport, Oklahoma
    Based on your background and your research calling yourself a "newbie" really isn't fair. You've dialed your prior experience into the Koi hobby quite nicely

    I'm also somewhat interested in the potential of the "anoxic" approach, but it still leaves the issue that JR and Mike expressed so well. The accumulation of other contaminants (like hormones) and the depletion of essential minerals in the water column. Those things are difficult at best to deal with in the absence of "new" water being introduced regularly.

    Two keys for keeping the cost/waste factors to a minimum are to make those water changes small and continual (as opposed to massive pump and dump changes) and making alternative use of the waste water. One of our members recently built a new pond that includes an irrigation pump for his yard for use in water changes. We do much the same with all of our water changes to keep our water use pretty neutral. With San Diego's mild weather that should work out fairly well for you as well.

    There are a lot of alternative for effective filtration and low energy consumption pumps. Airlifts can be a very low energy means for moving water that accomplish dual purpose in the process. There are also a lot of pumps on the market with comparatively high energy energy efficiency that can keep your operating costs down without sacrificing volume.

    The keys are to set your goals in terms of pond footprint and the number of Koi you wish to keep and then go about designing a system that will accomplish your purposes. It sounds very much like you are laying that groundwork very nicely and most of us only wish we'd had much foresight "the first time around"
    Larry Iles

  5. #5
    Join Date
    Jul 2009
    Mike, JR, Larry,

    Thank you all very much for the warm welcome and valuable insights.

    Quote Originally Posted by PapaBear View Post
    Based on your background and your research calling yourself a "newbie" really isn't fair. You've dialed your prior experience into the Koi hobby quite nicely
    I appreciate the compliment.....but I cheated. My formal education is in biology/chemistry/molecular genetics; a little bit of that stuff seems to yet be stuck in the gray matter, even after some years have gone by. More importantly, I have maintained a number of aquariums in the past (back when electricity was cheap and the parents were footing the bill anyway -- I miss those days!)

    Mike, I think you make an excellent point that the presence of nitrate -- which we can easily detect -- may serve somewhat as an *indicator* that a water change is due, and such a water change may remove/replenish OTHER factors which we cannot easily test for. I had not thought of that before.

    JR, thanks for the scholarly reply. You are right that I was mostly thinking of the "already solubilized nitrite on its' way to becoming nitrate," and there are other places to look in the leaky system you describe. Solid fish waste, dead bugs, uneated food -- all will contribute to the nitrogen load. Settling chambers, vortexes, seives, etc. might help me get some of that stuff out of the water column before it completely breaks down. Although -- due to the energy concerns -- I am trying to avoid lifting the water very high, it also does stand to reason that anywhere I can get the water to make a bit of splash through the filter will provide an oppurtunity to off-gas a bit of ammonia (a la Bakki).

    I hadn't considered a "foam franctionator" (by which I am thinking of the "protein skimmer," up-scaled to a pond application?) Protein skimmers were pretty common in the higher-end marine aquariums, but rarely seen (back in the day) on freshwater aquariums. I would have thought that such a method would get rid of some of the larger molecular weight DOCs, but can this reduce the ammonia/nitrate content as well?

    Larry, I have been reading of some really compelling water flow rates from some people who have been experimenting with airlifts (over on KoiPhen and KoiShack), and the energy savings -- I feel -- will probably inspire others (assuming electricity continues to get expensive). I don't want to get too *exotic* on my first real pond, but I may try to plumb this pond for a few *options,* such that I can try a couple of mad-scientist ideas -- keep them if they work, scrap 'em if they don't -- all without having to lift a shovel and re-dig. Airlift tubes and perhaps a few of these "anoxic" filter media plant baskets are the two things the spring to mind.

    Thanks again, all, for the really helpful replies to my query.


  6. #6
    Honmei KoiCop's Avatar
    Join Date
    May 2005
    Southern California
    Hello Paul . . .

    We installed both a sieve (Cetus) and a combo trickle-tower/protein skimmer unit last year (Clarity).

    Since we placed the Clarity unit on an existing skimmer circuit, there was no additional energy required to pump water to the top of the unit.

    Like it? Will never have a pond without a Clarity again.

    Here's our build thread, if you're interested:

    Cetus and Clarity Install . . .

    Best wishes,
    Member: AKCA, ZNA, KoiUSA, IKONA, Koi-Unit.

  7. #7
    Join Date
    Jul 2009
    Thanks, Don.

    Speaking of trickle-tower / protein skimmers, I was looking at Ethan25's "Phoam Phraxionator" thread just earlier today. Pretty impressive:
    Phinally Phinished the Phoam Phraxionator

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