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  • Sharing my experience with anoxic filtration

    I thought I'd make a.new thread separate from the thread MikeM started. I'm doing this only because I wanted to give my impressions on my thus-far 9 months of implementing anoxic filtration without the focus being lost into another fellow koi kichi's experience. I underscore 'impressions' so as to differentiate it from being a conclusion. Conclusion seemingly have a stamp of finality, whereas impressions are more malleable, and can change as more observations come over time.

    I'm not going to explain how anoxic filtration works. You can go to Manky Sanke's detailed and well-written explanation on it. And you can see some examples of its use in www.anoxicfiltration.blogspot.com of Dr. Kevin Novak.

    Here are my impressions:

    1. It isn't for the faint of heart. Because it's in essence a biofiltration system that can't be bought as a turnkey system, anyone planning to implement it has to be a DIY'er. While instructions on creating an anoxic filtration system are available and clearly explained on the web, there are still quite a few gotcha's that I liken to fine print in a legal document: You just have to face that situation to learn of it. It's all honky-dory until that point, and then you're kinda on your own, since you don't have a dealer and his warranty to lean on.

    2. Having said that, it is well worth the effort - if you are a patient person who can troubleshoot, and are not caught in the modern theory of being spoon-fed, aka 'delegating it to the (so-called) expert. In my neck-of-the-woods (sorry Al Roker), experts are a dime a dozen.

    3. It is understandable for the authorship/readership of koi-bito to be very conservative in its acceptance of anoxic filtration. I could see other websites to see examples of anoxic filtration in use, and it seemed to me that koi-bito was behind the curve. I kept this thought to myself, only because I felt there was something I'm missing. You could say I'm no longer the wide-eyed kid fresh off college and have learned to steer clear of dogmas and ideologies. Everything has to be taken with a grain of salt, and when it comes to the subject of biofiltration, this guardedness applies as well. Being a skeptic goes a long way. And Koi Bito is a steady ship.

    On the technical side now, here are my impressions:

    1. Test. If you can, do a pilot. Use an aquarium to test out your initial implementation of anoxic filtration. In my initial trial it didn't work. I couldn't get nitrite readings to go to zero. Imagine if I just jumped in and applied this in my pond. I would be shifting quickly my focus into battling koi getting sick of nitrite poisoning. A friend told me to use unbranded locally -produced (Philippine) zeolite cat litter, and I did after not being able to find any branded bentonite non-clumping cat litter. I gave it 3 months to finally stop the trial. Was I patient enough? I think so. I'm sure I wasn't instantly gratified.

    It was only that I happens to chance upon some stocks of Pura non-clumping cat litter in a supermarket that I resumed my trial. This time it worked. I'm glad I bought more sacks of this cat litter, as it turned out the supplier was just glad some dolt bought their remaining non-moving inventory. What was happening was that all the premium branded cat litters imported in are the clumping variety (unsuitable for anoxic filtration), since the non-clumping cat litter market had given way to the cheap locally-produced generic zeolite-based cat litter.

    As an aside, this was bad news for me as I am no longer able to procure locally the Pura brand of non-clumping cat litter, and so I am limited in the number of bcb (biocenosis baskets) I could employ. I have to think of taking a trip to HongKong to find suitable cat litter and have it shipped to me. Otherwise, I have no cat litter to increase my biofiltration capacity, much less to replace the existing cat litter in my bcb's.

    2. If shifting from nitrifier-based jap mats, consider starting with a hybrid system, combining anoxic with nitrifier-based biofiltration. I have two chambers for biofiltration in a multi-chamber filter system. The first one I put in anoxic bcb's to replace the jap mats, the second one I left the existing jap mats in place. The first reason is for the existing bio system to continue to do its job, while the anoxic filter cycles up and matures. Of course, with the bio capacity reduced initially, feeding levels have to be downward adjusted. The second reason is for the anoxic biofiltration (1st bio chamber) to kick in first before the nitrifier-based filtration (2nd bio chamber) so that anoxic filtration is allowed first crack at the ammonia, and the nitrifiers take the remaining ammonia/nitrites. This maximizes nitrate reduction. The 3rd reason, and I say this after the fact, is that my anoxic system works poorly in sunless and rainy days, and at night, and having the jap mats really help, as nitrifiers work with or without sunlight.

    3. Fines management is as important, maybe even more, with anoxic filtration than with jap mat-based nitrifier biofiltration. Fines left to block the surface of the bcb's seemed to interfere with the biofiltration when left to accumulate. It bears watching and the bcb's need regular attention. Luckily, help comes in the way of the jap mats that the bcb's displaced in the first bio chamber. It does a good job being a fines filter. In my setup, I had the fortune of having a k1 static media bed to filter mechanical particles that escape the settlement chamber. A piece or two of jap mat strategically placed before water gets to the bio chambers goes a long way in easing the pain of constantly cleaning the bio chambers. Of course, you'll have to clean the jap mat.

    4. The more plants in the bcb's, the better. Plants will directly use the ammonia. This lessens dealing with nitrites and nitrates.
    5. Plant roots are important. When you eventually have to trim the roots, you will impact the ammonia clearing capacity of that basket. Don't do the baskets all that once. Stagger it.
    6. When you lift the bcb out of the water to clean it, the mere act of removing it from being submerged changes the anoxic condition and the bacterial relationships related to clearing ammonia. Keep this in mind, and if possible, clean the basket submerged. I use a siphon to suck out the dirt on top of the basket. Since cat litter will be sucked in, keep a container on the other end of the siphon so the cat litter can be cleaned and reused.
    7.If not on a hybrid system, be mindful to feed only during the day, and to be more strict on it, only when the sun is strong such as in the hours when a solar cell produces electricity strongly.
    8. If not in a hybrid system, i. e. purely anoxic, double the needed baskets to give allowance for cleaning, when the baskets cleaned experience low ammonia clearing capacity.

    That's it. Again, I'm no expert. These are my impressions. I can very well be wrong on many points. Hopefully, not all of them.
  • #2

    Yerrag, do you have before and after test results of water parameters, including water change rates? It would be helpful to understand how effective anoxic filtration has been in your setting. I know you have changed around filtration and such over the past 24 months, so it may not be possible to reach definite conclusions from the data, but it would still be helpful.

    Comment

    • #3

      I would roughly say that my water changes didn't change much at a 3% daily rate. Before, my nitrate readings would range from 40-80 ppm and phosphate would stay constant at 5ppm. Nowadays, my nitrate readings would range from the occasional 5ppm to a more frequent 10ppm. Over the 9-month period since I changed to anoxic-nitrifier hybrid, my phosphate readings have steadily declined from 5ppm to a current 1ppm.

      Comment

      • #4

        It would only be fair to note that on rainy days, I used to have no qualms about feeding more to the koi. In fact, I was warming to the idea of using the rainy season as my 'new' growth season for koi. But changing to the anoxic system put a halt to my plan.

        Now, I would be feeding less on rainy days, and during rainy season. The rainy season came late this year this August. No drought is always good news, especially with El Niño around. I may be wrong, and I still need more observations, and II mneed to have only one control parameter change as much as possible, but it seemed that lack of sunlight hampers the operation of my anoxic filter. If that is indeed the case, I would have to lessen my feeding levels. Else I end up with higher ammonia levels in the water.

        However, I am qualifying my impressions as there are other factors in play that could affect my observations:

        1. I have been nonchalant about putting the right plants for the bcb's. The plant growth isn't lush. It can be better.
        2. I had cleaned my jap mats thoroughly with a high pressure washer. Although the water I used was from the pond, a lot of nitrifiers would have washed off and this could be the cause, and this coincided with my experiencing higher ammonia levels that happened to occur at the start of the rainy season.
        3. I also pulled out the roots of a plant from a bcb. If the roots were still active in clearing ammonia, I may have caused a significant loss in the biofiltration capacity of my filter. Considering that I was materially constrained in adding more bcb's, my biofilter is very sensitive to slight changes in conditions. If I have more bcb's in place to have more allowance for disturbances, my biofilter would not so easily give way to higher ammonia levels.

        Comment

        • #5

          I have an anoxic leg in my pond filtration circuit. I agree in large part with what yerrag says. To that I might re-emphasize that very good mechanical filtration prior to the anoxic chamber is a must. But even with that some fine debris will get through and over the months lay down a fine layer upon your baskets. Like yerrag says (and I add to) cleaning the chamber is a learning experience. I first lower the water level in the chamber. With some water still covering the baskets I uses a shopvac and vacuum off the dirty top layer. Most baskets have good size rock on top so if done with some care this works pretty well. I then lower the water further and take out about a third or half of the baskets and refurbish them with cleaned off rock, some new cat litter. Kitty litter and debris will have settled between the baskets, clean it out. Wet the baskets, put them back in to the chamber. This makes the least mess if the baskets are put back in to an empty chamber and the water is then added. Plants in the chamber are a plus. I cleaned the chamber well this spring and cut the plants back, they then flourished, but with the shortening of day I can see some decline. Four babies from this springs spawn found their way to the chamber, they do very well in there (if they can avoid the pump long enough to get big).
          Attached Files

          Comment

          • #6

            The general comments posted around the internet give mixed experiences with anoxic filtration. Conscientious data keeping is lacking, and folks are often making up their own shortcuts rather than following the guidance of the leading proponents. Whenever a new practice or technique comes along, there is a tendency for it to become faddish, with overly exuberant claims made by some... often within just a couple of days, which undercuts the reliability of anecdotal observations. Then the naysayers jump in and a new concept gets trashed mercilessly. This is all good, even if argumentative, since the practical ideas that work survive.

            We've now had anoxic filtration around for a number of years. It seems to me that it has failed in more instances than it has worked, perhaps due to folks not properly setting up initially and often they have not engaged in the maintenance Rob describes. The lowering of nitrate described by Yerrag is impressive. Whether or not the feeding levels are as much or more of a factor, something is doing well. The decline in phosphate levels to 1ppm is actually more interesting to me. This is a low level, lower than I would expect reduced feeding to accomplish. The lowering of phosphates is consistent with the theory behind anoxic filtration. This was explained in Novak's blog a couple of month's ago:


            "Actually, most phosphates in our ponds are due to food fed and the quality of tap water used for evaporation makeup or water changes. However, it has been said anaerobic areas, were obligate anaerobic heterotrophs live, accumulate phosphates. As a matter fact, the anaerobic area with its lower pH and redox is an efficient user of the oxygen electrons tied to the phosphorus element; therefore, phosphate is quickly reduced to other phosphorus molecules and ions.
            Therefore, phosphate accumulation anywhere where it is not attacked for its oxygen, suggesting that in more aerobic and anoxic bed areas there would be greater accumulation since oxygen is readily available. However, that is also not accurate! In those areas, it is mostly bound to calcium and manganese (a trace element in Laterite) where it is quite stable because it is very easy to maintain its “charge” balance. Therefore, phosphates are usually not available for uptake in substrates unless associated with reducing conditions.
            [Ed: The above paragraph also tells you why the bacteria do not employ the ponds oxygen. The bacteria will, as you know use the oxygen from phosphates and Nitrates, too. This explains why Dr. Franco found that by adding a BCB to his Nitrate and phosphate laden aquarium, that it completely wiped-out his phosphates to zero. People must understand that these bacteria are smart little buggers and can utilize so many different recourses for their food requirements and oxygen provisions.]
            I believe that a nearly complete recycling can be achieved in a pond equipped with biocenosis clarification baskets. The fact remains that grain size and depth of such, play a major role in the class of bacteria that inhabit the biochemical pathways of the substrate of each basket. Nevertheless, when the right percentages of each are present, the substrate world has a very positive effect on the overall pond water mass and will therefore make it suitable for aquatic animals! "

            I am not ready to accept anoxic filtration as a practical approach for use with koi ponds, but I do accept the basic science behind the concept.

            Comment

            • #7

              Adding an anoxic leg to koi pond filtration can in theory complete the nitrogen loop releasing it as N2 into the air. This could save a lot of water by avoiding the water changes that are the commonly employed in “the solution to pollution is dilution” regime.

              Where water is a scare resource anoxic can be an attractive option. There are other ways to get the nitrate out of pond water other than dilution and anoxic filtration. These methods can be highly technological as compared to dilution or anoxic filtration. Resins, distillation, reverse osmosis, and other technical innovations tend to require significant energy expenditure and so are not just costly upfront but also to run.

              Perhaps the biggest drawback to anoxic filtration is that it is DIY (unconventional and relatively cheap). It is not mats and beads and vortex and UV, it is “just” clay submerged in baskets. And that clay is conveniently and cheaply available as non-clumping kitty litter which is a pain to work with. Not impossible but really messy until you figure it out (and then it is still somewhat messy). The clay does dissolve to some extent. It is dusty. It is small pieces and leaks out of the biocenosis baskets. I know of at least one club member who gave up on anoxic because of how hard kitty litter is to work with. It is DIY. I do understand why this clay is the preferred medium, but it is not an ideal medium. And the relatively small amount of laterlite clay that is required at the core of the biocenosis basket is not cheap (for dirt). The foot print of an anoxic filtration chamber is not small (mine is 4’x8’x2’). I would highly recommend making it deeper, stacking the baskets and including a bottom drain for cleaning.

              These difficulties notwithstanding I am generally pleased with my anoxic set up. It requires maintenance, but way less than a mat or a bead filter. It takes up space, but is another small pond and the water hyacinth, the elephant ears and the papyrus look pretty good growing out of a clear flowing pool. I move around 5000 gallons an hour through it and throw it over a waterfall into a stream. My nitrates are lower, they were never that high. But my pond is a poor test case since it is a mixture of systems that are running in tandem (BD/vortex/anoxic/pump &BD/pump/bead/UV). Contrary to the anoxic concept flushing the vortex and the Bead filter makes a significant water change. And it also rains a lot in Florida.

              Comment

              • #8

                This could save a lot of water by avoiding the water changes that are the commonly employed in “the solution to pollution is dilution” regime.
                Exactly how? This filtration technique may reduce nitrates; but there are other pollutants given off the routine bio processes in the eco-system and failing in from the surrounding environment. How does avoiding a water change reduce pollution and bring in KH and needed electrolytes needed for a healthy system?

                http://www.koi-bito.com/forum/main-f...-new-pond.html
                Koi keeping is not a belief system; it is applied science with a touch of artistry.

                Comment

                • #9

                  There is no rule of thumb for water changes?

                  Comment

                  • #10

                    Originally posted by MCA View Post
                    Exactly how? This filtration technique may reduce nitrates; but there are other pollutants given off the routine bio processes in the eco-system and failing in from the surrounding environment. How does avoiding a water change reduce pollution and bring in KH and needed electrolytes needed for a healthy system?

                    http://www.koi-bito.com/forum/main-f...-new-pond.html
                    Good point. Let's enumerate each of these pollutants, and then discuss each one in terms of how they can be eliminated without so much as changing water. Let's say Rob is sending a crew to Mars and they have a koi pond with them, so we're talking of a closed system here.

                    Comment

                    • #11

                      No problem. The koi would use the type of water processing used by the crew where their urine is filtered and purified enough to be drinking water. I assume it must be some high end RO unit or something similar. But the water for the koi would have to be further managed for pH, GH, and electrolytes to ensure the koi's health. I would if they would pack Kenzen or Saki Hikari or.....?
                      Koi keeping is not a belief system; it is applied science with a touch of artistry.

                      Comment

                      • #12

                        Originally posted by MCA View Post
                        No problem. The koi would use the type of water processing used by the crew where their urine is filtered and purified enough to be drinking water. I assume it must be some high end RO unit or something similar. But the water for the koi would have to be further managed for pH, GH, and electrolytes to ensure the koi's health. I would if they would pack Kenzen or Saki Hikari or.....?
                        I spoke too soon. The pond still needs some water changes, as koi will still produce solid wastes. And those waste needs to be discarded, water along with them. But other than that, let's say no more water is changed in an anoxic system.

                        Ammonia and nitrites would be zero. Nitrates at 10 ppm and phosphates at 1 ppm. What pollutants are you referring to that would require more water changes? Note also that kH declines very slowly when the anoxic filter has plenty of plants that use up ammonia directly, leaving less ammonia to be converted by nitrifier bacteria.

                        Would there be plenty of DOCs? If a foam fractionator is being used, how much DOCs would remain in the water column?

                        Will the water become stale? How would it become stale? What can be done to refresh and renew the water so that it becomes like spring water?

                        For me, it would be because water can still become stale, even if all the water parameters are met, that make water changes necessary. Water may lose its vitality, similar to microwaved water, that its life-supporting qualities are stripped from it. So, I agree that more water changes are better.

                        But I believe that with the use of anoxic filtration, the volume of water changes needed would be less than with the use of a nitrifier-based based biofiltration system. Less nitrates, less DOCs, more stable kH- all making the case for anoxic filtration.

                        Comment

                        • #13

                          Originally posted by RobF View Post


                          Perhaps the biggest drawback to anoxic filtration is that it is DIY (unconventional and relatively cheap). It is not mats and beads and vortex and UV, it is “just” clay submerged in baskets. And that clay is conveniently and cheaply available as non-clumping kitty litter which is a pain to work with. Not impossible but really messy until you figure it out (and then it is still somewhat messy). The clay does dissolve to some extent. It is dusty. It is small pieces and leaks out of the biocenosis baskets. I know of at least one club member who gave up on anoxic because of how hard kitty litter is to work with. It is DIY. I do understand why this clay is the preferred medium, but it is not an ideal medium. And the relatively small amount of laterlite clay that is required at the core of the biocenosis basket is not cheap (for dirt).
                          Another drawback I see is sourcing of cat litter that is guaranteed to work in an anoxic system. Even if you find one brand that is suitable, you cannot be assured of the same properties in a future purchase of the same brand. The problem is that the primary use is as cat litter, and the requirements for use as cat litter is much more lax than the requirements for use as a material for anoxic filtration. There is the risk that someday I might just find myself with a biofilter that is not doing its job. What is needed is a brand that guarantees the suitability of its product for use in anoxic filtration. There actually are some products like that, but they can't be priced like regular cat litter.

                          Comment

                          • #14

                            I have seen discussions where someone who ended up with a huge mess was told they used the wrong cat litter. What is recommended is a baked clay that will not turn into mud or dissolve in the water. Certain cat litters happen to have the recommended properties, but apparently most do not. A blurb on the subject:

                            "Cat litter.

                            Guidelines are that you need unscented litter that has NO anti-bacterial additives. It also needs to be NON-CLUMPING. Read the labels to find out these things. If it says 100% pure clay on the ingredient list, and nothing else, that would be best. The cat litter I found here in Canada also has diatomaceous earth as an ingredient and Dr. Novak thought that would be fine to use, as well.

                            In addition, it needs to to be baked clay and the labels do not tell you this. You have to buy a sample package of a possible candidate litter (one that fits the guidelines mentioned above) and test it by putting some in a jar of water for a few days. A baked clay will still be nice and granular after being submerged, the grains holding their original shape. Unbaked clay will turn into soft mush. DO not use a litter that turns into mush!

                            People in some countries have a difficult time finding a good clay. In the US and Canada it's safe to use Walmart brand "Special Kitty" Non clumping. Good luck!

                            ....Tryout your cat litter before you buy a tun of the stuff."


                            So it is the really cheap stuff you want to check out. Fact that it is cheap does not mean it is what you want, but you definitely don't want the higher priced ones. I think all the brands at my local supermarket are clumping or scented or promote some additive. I know when you go down that aisle, the scent is in the air.

                            Comment

                            • #15

                              Originally posted by MCA View Post
                              . How does avoiding a water change reduce pollution and bring in KH and needed electrolytes needed for a healthy system?
                              The Anoxic filter does not consume KH so there is no need to add anymore.

                              Comment

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