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  • Anoxic Filters: Updates from anyone?

    A few years ago, there was a lot of advocacy on the boards for using anoxic filters to remove nitrate and otherwise help maintain water with fewer water changes. A number of hobbyists said they were going to give it a try. I have not heard much about anoxic filters for quite some time, so I'm guessing it did not work out in practice. But, perhaps I've just not been visiting the right boards on the right day. I'd request anyone who tried the concept report on their results.


    (Nitrate seems to be a hot topic on a number of boards this week, so this came to mind.)
  • #2

    I know its a ways for you but chicago pond tour(MPKS) is coming up in few weeks and there the person that came up with it is on tour plus seeing book i see few others have it and on tour.

    i have not been on the tour in many years but did visit his place and must say fish looked good in VERY small area plus few others had it for few months to like a year??? and they were happy with it.

    So outside of that i am no help
    Paul Korf

    member of:
    Midwest Pond and Koi Society
    Louisville Koi club
    IKONA

    Comment

    • #3

      RobF 's latest upgrade last year was Anoxic. He had some issues with cycling the new pond, but I have not heard of any updates. He is in England on "holiday" with his lovely wife Hazel, at this time. He is scheduled to have the next Orlando Koi Club meeting, which I am trying to get rescheduled to September.
      Recently, a couple from the club, built a 6,000 gallon pond with a takeoff from Rob's design. They were having problems with water quality, which I attribute to cycling. I refered them to Rob, since I have very little knowledge of this system.

      Darrell

      Comment

      • #4

        Anoxic bio-filtration has always been a subject of much discussion with little objective data to either support or to undermine the assertions. The chemistry and the biology of the process are not in dispute, the questions that arise are in regard to the effectiveness of the practical implementation. The classic bio-filtration process reduces the level of toxic ammonia resulting from fish respiration by employing naturally occurring bacteria to 1. convert the ammonia to nitrite and then 2. This nitrite to even less toxic nitrate. Nitrate levels are then in turn reduced by dilution (water changes). As thousands of koi ponds attest this works. But it does mean that the fish are always subject to some nitrate and the waste water has a cost and it requires time and attention. Anoxic bio-filtration attempts to side step these deficiencies by bringing to bear a third cadre of bacteria to 3. Reduce the nitrate to the even less toxic nitrogen gas. Anoxic bacteria live in very low: 1 ppm levels of oxygen (not anaerobic) whereas the bacteria of processes 1&2 are aerobic. There is plenty of write up on the implementation to be googled.

        All that said my pond is really not much of a test case. When I tripled the volume of mypond from 5K to 15K I added an anoxic filtration pond. With 32 baskets it should just be big enough to handle the addition. But I left in place the AquaUV modeled system of the 5K pond (pump, UV, Bead) which is contrary to the full anoxic concept. And there are several planted containers of water lilies (3) and papyrus (2) to further confound conclusions. However I can offer these observations. My fish are healthy and active, the water is usually clear despite being in full sun for much of the summer’s day. Strong mechanical filtration prior to the anoxic chamber is critical since anything that gets through will settle between the baskets and can foul the system. I have a 450 gallon settling chamber it may be enough, but once again flushing this chamber confounds conclusion because it introduces significant water change. It takes a lot of anoxic baskets to do the job and so it is tempting to use too few. Kitty litter works but it is not specifically designed to be submersed. The Laterlite used as the basket core can be expensive and so it is tempting to use too little. Put a drain in the bottom of the anoxic chamber so debris can be flushed (maybe every 3 months). Overall I am satisfied with the performance of the pond and of the anoxic portion and I would not discourage anyone from trying it out. But do your homework, don’t under design, and as with any new pond it will take some time for the system to mature.
        Attached Files

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        • #5

          Build a shower filter instead with porous media that has lots of surface area for aerobic bacteria and internal space for low O2 dependent bacteria. You need media that lets water flow over and through.

          How does an anoxic filter raise DO or reduce CO2?
          Koi keeping is not a belief system; it is applied science with a touch of artistry.

          Comment

          • #6

            Anoxic bio-filtration does not raise DO or lower CO2, as you indicate for this aeration is key. And the aerobic bacteria in the outer layers of the clay of the portion of the biocenosis basket would benefit. However anoxic filtration is so named because the inner layers of clay are oxygen deficient and are home to a class of bacteria that harvest energy from the (nitrate) waste of their aerobic predecessors.

            The purpose of bio-filtration is to reduce the toxicity of nitrogenous waste. Convention bio-filtration converts ammonia to nitrite and then the nitrite to nitrate. This nitrate in aqueous solution is then diluted and/or flushed. Instead of using dilution and water change an anoxic segment seeks to further process this nitrate to N2 and release the nitrogen back into the environment as a gas. Kitty litter is a preferred media because it is clay, it has a huge surface area, it is cheap, and it is readily available. It is not necessarily the ideal media for water, but given the current level of development of the anoxic bio-filtration concept it sufficient unto the evil thereof. Anoxic filtration is likely to remain the eccentricity of a few if and until a commercial product is developed and promoted.

            Comment

            • #7

              I know i have the DVD but wasn't the use of kitty litter because something was positive and something negative and why this worked
              (sorry i am not remember the chemistry of what was what)
              Paul Korf

              member of:
              Midwest Pond and Koi Society
              Louisville Koi club
              IKONA

              Comment

              • #8

                Originally posted by pskorf View Post
                I know i have the DVD but wasn't the use of kitty litter because something was positive and something negative and why this worked
                (sorry i am not remember the chemistry of what was what)
                I think what you are referring to is it was said that; "Positively charged ions/molecules dominate bulk waters. Negatively charged sites in the clay dominate each basket and attract the positive ions."

                Comment

                • #9

                  The Anoxic concept is scientifically sound. As Rob stated, it is the practicality of implementation and effective design that is the challenge. In a natural water body there will be an anoxic layer in the bottom mud which converts some substantial portion of nitrogeneous waste (but not all) to N2. While clay certainly adsorbs nitrogenous ions, I am in doubt concerrning how deeply that will occur. I think it likely that only a small percentage of adsorbed ions will migrate much from the surface of the clay. The anoxic layer will be quite close to the surface given the density of clay. Most of the clay would be anaerobic, but I think little of anything would move through the clay to the anerobic zone to create the noxious byproducts we so want to avoid. Heavy plantings in the clay could reduce this negative aspect further since heavily rooted plants, like waterlillies, carry oxygen to the root zone. In organic media, the breakdown by anaerobic processes is too great for plants to offset the negatives. Clay would be materially different. Altogether, however, I do not believe there is sufficient clay surface area (which translates into the anoxic layer) to have much noticeable effect in the typically stocked koi pond. So, I would expect there is no material reduction in water changes accomplished, which is the only real benefit of the anoxic concept. If it was effective, there would be benefits for those in areas where water is becoming costly, which seems to be more places every year as population grows. (I think re-processing water outside the pond through use of oxidizers [even ozone] would be more effective.)

                  Absent prohibitive water costs, I would not adopt the anoxic method even if a technique for effectively implementing it was developed. I consider nitrate a negative, albeit comparatively harmless; but as important in my mind is that nitrate serves as a marker for the build-up of contaminants of all sorts. I cannot test for hormones, all the byproducts of decomposition, metals, leachings of plasticizers and such. If through water changes I keep nitrate low, I figure I am keeping whatever else there is similarly low. But, then, I'm kinda an old guy set in his ways who has great faith in water changes.

                  Comment

                  • #10

                    I think there might be some anoxic areas in rock and gravel filters.

                    Comment

                    • #11

                      Very likely
                      Koi keeping is not a belief system; it is applied science with a touch of artistry.

                      Comment

                      • #12

                        I am not an advocate for anoxic bio-filtration, I am more of an eccentric (you know like people who keep koi!) bordering on an armchair mad scientist. Anaerobic media is not an issue with the biocenosis basket as implemented in Novak’s design: there are no anaerobic spaces. We are all familiar with the smell associated with anaerobic processes, there is none of that. Each of the roughly 10” cubes of clay are surrounded by aerated water. One of the things that makes this implementation of bio-filtration conceptually, fundamentally, different (in addition to using anoxic bacteria to process nitrate) is that it functions not by flow through (as with pad, brushes, beads, TT) but by diffusion. The ammonia and oxygen do not flow into the clay they diffuse into and through the layers driven by a concentration gradient and the electromotive impetus of the laterlite core. In the end it is bio-filtration we want, and if you build an anoxic bio-filter in accordance with Novak’s design it will provide bio-filtration (and the aesthetics of the planted chamber is often superior to a black box).

                        Comment

                        • #13

                          wondering what would happen i you used chicken grit (oyster shell kind)
                          if you get the benefit of anoxic filter plus the calcium benefit
                          Paul Korf

                          member of:
                          Midwest Pond and Koi Society
                          Louisville Koi club
                          IKONA

                          Comment

                          • #14

                            Originally posted by MikeM View Post
                            ...Absent prohibitive water costs, I would not adopt the anoxic method even if a technique for effectively implementing it was developed. I consider nitrate a negative, albeit comparatively harmless; but as important in my mind is that nitrate serves as a marker for the build-up of contaminants of all sorts. I cannot test for hormones, all the byproducts of decomposition, metals, leachings of plasticizers and such. If through water changes I keep nitrate low, I figure I am keeping whatever else there is similarly low. But, then, I'm kinda an old guy set in his ways who has great faith in water changes.
                            The idea of yet another 'filtering' layer in the ammonia/nitrogen/nitrates daisy chain is certainly a fascinating concept. I'm certainly no water quality chemist or have near the koi keeping experience you all do, but I just wonder about the time, money and effort required to take this to a plausible, workable solution for nitrates, given that water changes achieve the same objective and so much more.

                            I would think all the trace metals and minerals that fresh water introduces to replenish these minute but vital nutrients would, alone, make water changes all the more attractive as the alternative of choice. Unless your source water is exceedingly 'bad', it would seem these additional elements are important to the creation of what JR, I seem to recall, used to refer to as 'living water'. (JR, JR, wherefore art thou JR?)

                            And you aren't 'old school' at all in the faith you put into water changes, MikeM. Every successful koi keeper I know, young or old, preaches it like it's the 11th commandment of Moses, and the first commandment in koi husbandry.

                            Comment

                            • #15

                              If fresh water is so expensive or such bad quality as to be prohibitive, then I suggest the owner should give up outdoor fish pond keeping and go smaller scale with indoor aquariums where they can provide high quality fresh water on a regular basis. Convert the outdoor ponds to water gardens or water features where water quality is not so important.
                              Koi keeping is not a belief system; it is applied science with a touch of artistry.

                              Comment

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