ovo je napisao isti onaj covjek koji je razbio mit o nitrifikaciji i njenoj komercijalizaciji, dr. tim hovanec ...
zasto je komplicirana i koji su problemi u balansu?
Denitrification, on the other hand, will not proceed unless the aquarist active provides, and continues to promote, a special environment which has a low redox potential. First, an anaerobic area must be provided. Oxygen will kill the bacteria, halting the process and necessitating the restarting of the filter (meaning the bacteria have to become re-established). This is not an easy thing to do. How does one create such an environment. Where should you put it in the tank? How do you assure that it remains anaerobic. Unfortunately, I have no answers readily available. One option is to chemically strip the oxygen from the water but this is expensive and involves chemicals which might not be compatible with the rest of the system.
Another problem is to provide a constant source of the organic carbon required by the bacteria. This means mixing it up and delivering it at the correct infusion rate which will change over time. There is not enough naturally occurring organic material in an aquarium to keep the process going. Exactly how do this for an aquarium is not well documented.
Lastly, there is the problem of balancing the system so the intermediate products do not accumulate. The first product produced when nitrate is reduced is nitrite. As mention before, this is a toxic compound and it should not build-up in an aquarium. In many denitrifying systems, nitrite is a constant problem. The reason is usually an insufficient (incorrect) assemblage of microorganisms. The problem is providing and maintaining the correct assemblage of microorganisms. How to do this is again not well known. What is known is that redox potential can be an important indicator. Denitrification proceeds well within a range of redox values but if the redox gets too low than sulfate will be reduced to hydrogen sulfide which is a poison. Usually the cause of a redox value being too low is a lack of substrate for the bacteria to utilize. Thus, one has to carefully control the flow of nitrate and organic carbon into the system. To much and oxygen may enter it, too little and there won't be enough and sulfate reduction can occur.
sta misli o DIY denitratorima...
Does all this mean that denitrification should not or cannot be done by the hobbyist? The answer is no. But the hobbyist should know beforehand about the myriad of potential problems associated with denitrification. Constant monitoring of the water quality is needed so the process can be tracked and if needed, corrective action taken. Detailed notes should be taken so that reasons for successes and failures are known. In this way you can repeat the positive but not the negative. Further, your notes could be the basis for your own article about denitrification.
nesto o gotovim proizvodima ...
Finally, there are a few commercially available systems for denitrification. They range from simple to complex. Some 'systems' are basically nothing more than a pile of granular media that is allowed to sit in the sump of a tank without being disturbed. The manufacturers of this say that the inside area of the pile will go anaerobic and denitrification will commence. My experience with these systems is that they do nothing towards lowering the nitrate levels in the aquarium
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nesto o tipu ovog "arsovog"...
Other systems for denitrification involve a sealed chamber through which a portion of filter water is directed at a very slow flow rate. There is a separate tube in which a pellet of organic carbon is added periodically. These systems must run for a long time before the water exiting the system slow any signs of a nitrate concentration lower than the inflow water.