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Thread: Nitrification

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    The nitrogen cycle or nitrification as it’s properly called is the process that keeps the water in your aquarium healthy and safe for your fish. Simply put, its’ aerobic chemolithic autotrophic bacteria‘s way of using the chemical energy in inorganic ammonia to fix carbon…..the oxidization of ammonia/NH3 to nitrite/NO2 to nitrate/NO3. Most other bacteria, heterotrophic, get their carbon from organic sources…..decay/mineralization ….simple isn’t.

    Until fish are put into a body of water, it's fairly sterile. Once the fish go in, ‘’the cycle’’ starts. This cycle can take anywhere from 6 to 12 weeks to complete depending on the water temperature, O2, pH and KH levels, while the bacteria get established. These bacteria are sessile and don’t inhabit the water column, so transferring old water around makes little difference.

    While they colonize every surface in the tank, along with dedicated bio-media in the filter, the levels of NH3 and NO2 will rise affecting the fish. The lower these levels remain, the better.

    The better way is to use pure ammonia…no stressing out fish…..fishless cycling. Another way is to transfer established bio-media around between tanks or add new media to an older established tank. Keep in mind though, that regardless of how much media is on a tank, the fish are still only producing X ppm of NH3, so the media can only get established to a certain degree.

    From the beginning, the fish give off the ammonia, NH3, from respiration via their gills, about 75% >80%, through osmoregulation and diffusion. The small balance comes from very weak urine. Keep in mind that freshwater fish do not drink water, so don’t pee very much. They actually fight to keep water out of themselves. The actual amount of NH3 they produced will depend on the protein level of the food being fed and the amount fed, as there is a direct relationship between the two. Therefore fish loads starting out should be kept low and feeding to a minimum, if fish are being used to cycle the tank. You should never buy a full load of fish for a new tank.

    Decaying organic matter such as, uneaten food, rotting plants, or dead fish also contribute to ammonia levels, via the mineralization process. So good house cleaning should be followed.

    Ammonia levels will start showing up a week to ten days after the fish are introduced and will continue to rise for several more weeks. While this ammonia/NH3 is building up, bacteria, Nitrosomonas sp, are also developing. This bacterium oxidizes/eats, the ammonia, converting it into Nitrite/ NO2. Once there are sufficient numbers of this bacteria to oxidize all the NH3 being produced, the levels will fall to 0.0ppm. This will take 4 to 6 weeks.

    During this time both NH3 and NO2 test kits should be used regularly.

    Ammonia is quite toxic, especially at higher temps and pH levels, greater than 7.2, so care should be taken to maintain pH levels in the lower ranges, during this time. If NH3 is allowed to build then it will irritate the fish’s gills, fins etc., and if levels are high enough it will prevent the fish from diffusing its internal levels of ammonia into the surrounding water. The fish will poison itself from the inside. This is a very common problem in shipping water when fish are being acclimatized.

    The lower the pH the more the ammonia will exist as ionized Ammonium/NH4, which is harmless to fish. It’s not capable of being absorbed by the fish via the gills and will not burn the fish or its gills. This is why shipping bag water may be loaded with ammonia and have little effect on the fish. The rise in the CO2 turns to carbonic acid in the water and drops the pH which converts NH3 into NH4.

    Ammonia should be tested for and the fish protected from it, using a chemical binder such as Amquel, Ammo Lock 2 or other similar products. Fish that are showing signs of high levels will be sitting on the bottom, gasping, display red streaks in their fins or body, generating and dropping their slime coat/cuticle…looking brunt and just generally stressed out with fins clamped. Water changes will help if the levels are extremely high.

    The result of the ammonia being oxidized is Nitrite, NO2. At this time a second type of autotrophic bacteria starts to develop called Nitrospira sp... This bacterium oxidizes the nitrite/NO2 into nitrate/NO3. It again, can take anywhere in the 6 to 12 week range for nitrite levels to peak and then fall to zero. This can be a very stressful time for the fish, as the ammonia levels are also high or rising and now a 2nd toxin is building. …but it’s rare for a fish to die directly from the nitrification process if some attention is being paid to it.

    It was long held that the bacteria called Nitrobacter did this conversion but recent research by Dr. Timothy Hovanec has shown this to be wrong for fresh water. The species resposible in freshwater is Nitro Spira

    Once these bacteria are established both ammonia and nitrite levels should read 0.0ppm at all times. The oxidization process is almost instantaneous, so little dwell time is needed with in the filter.

    Higher temperatures and pH levels will help the Nitrospira to develop quicker, but pH levels and temp should not be raised until the ammonia levels have started to drop though.

    This again is a highly toxic chemical for the fish. It can impede the fish's ability to breathe/ move O2 throughout its blood system. All fish have chloride ion pumps/receptors located in their gill lamellae. Using chlorides is a normal and essential part of their physiology as are many other elements. The Nitrite ion and the Chloride ionic structure are similar and these receptors don’t know the difference. So if there are lots more NO2 ions than Chloride ions, in the water then they get picked up along with the chloride ones. The NO2 that’s absorbed at the gill surface then slowly affects the blood hemoglobin’s ability to carry O2. It changes it into an element called Methaemoglobin.

    Basically one part of the red blood is iron based and when excess O2 is introduced, the blood gets oxidized…it rusts. When this happens it slowly looses it ability to carry O2 and the fish slowly suffocates. This does not happen quickly at all. It’s a slow cumulative process. Fish experiencing this will be breathing fast maybe piping at the surface.

    The gills and blood will have a rusty brown colour. This symptom is called Brown Blood Disease.

    There has been some research done that maybe Methylene Blue may reverse this disease but it very easy to prevent it in the 1st place.

    The fish can be protected from high nitrite levels by using plain old salt, at a rate of about1 teaspoon per 1gallon of water; this is approx 0.1% salinity level. Since salt is sodium chloride/NaCl, the excess chloride ions added to the water via the salt will then out compete the NO2 ions at the gill chloride receptors preventing it being taken up by the fish. Some species of fish are more sensitive to NO2 levels than others, so more salt should be added. Also, the higher the NO2 level, the more salt that should be added.

    Lower levels may be used if there are salt sensitive fish or plants in the tank, but water changes should then be included with the salt. Any salt can be used but it should be free of any additives or anti-caking agents, like YPS, yellow prussiate of soda. Iodized table salt if fine also.

    The last chemical produced is Nitrate, NO3. This chemical is not generally toxic to the fish but levels should be kept below 20ppm as high levels are an indication of over all poor water quality. This can be accomplished using water changes of at least 30% per week, lots of floating plants or large Trickle Towers.

    After 8 to 12 weeks, sometimes longer, both ammonia and nitrite levels should be at 0.0 ppm, if they are not then something is wrong. Either the fish load is too heavy for the bio filter; the flow through the filter is too slow, too much uneaten food laying around, etc. At that point you should start cleaning, increasing or changing things till you find out what's wrong.

    As mentioned these bacteria grow on every surface within the tank and the filter, including the fish, but they need somewhere to colonize in large numbers. This is where the bio filter comes in. There are quite a few different bio media on the market, from bio-balls, PVC shavings or ribbons, beads, porous mats, plastic scouring pads glass sintered tubes, open pore sponges, etc. Whichever one is used, there should be a lot of it. All filters should have a section dedicated to the bacteria and this section should not be disturbed unless absolutely necessary. When the bio media has to be washed off, then tank water should be used. Do not soak in chlorinated water, as this will affect them.

    The bio-film will grow to the levels of food ie: ammonia, that’s available to them. Adding a few new small fish like Platy’s, Guppies and the like would have little to no affect on established bio-film. Adding large fish like Oscars, then you may see a spike in the NH3 and the NO2 levels but this would be very short lived…a 24 hour spike maybe and nothing to worry about. It would not kill any fish.

    Once well established, the bio-film/matrix is very tough and hard to negatively affect. The bacteria, molds, fungi and any other microbe that forms the film are well adhered to the media. Think of your teeth; you brush everyday but still have to hit the dentist for cleaning to get what you didn’t. It takes a lot; such as some heavy chem use or antibiotics to knock them well back and to get a tank/bio-media to have a prolonged period of re-establishing itself. There are many anecdotal stories of bio- media being allowed to dry out, stored away for months and then re-establishing itself with days….it’s tough stuff once established. It may take a full year for bio to get well established.

    These bacteria grow their best when they have higher pH and KH levels and lots of oxygen. A pH of 7.8 or greater and a KH of 80ppm or greater will help them along just fine. As pH drops below 7.0 the bio-film and it's bacteria start to oxidize less and less ammonium, with all nitrification stopping with the pH around 6.0 or slightly lower. If the tank should run out of KH, which these bacteria utilize and the pH ''crashes''/ drops suddenly, then a lot of the bio-film will be killed off, resulting in spikes of NH3 and then NO2. This is one of those situations where the tank might re-cycle for several days to a week to get the bacteria back up to speed. Fish that survived the crash would have no problem surviving the spikes for the next few days after the KH and pH were corrected……… So pH and KH should be monitored on a regular basis. Keep in mind also that nitrification is an oxidization reaction and requires lots of O2 so oxygen levels should be at temp saturation levels at all times.

    There are a lot of products on the market that claim to have live bacteria in them to speed this cycle up, but most of them do nothing regardless of what the bottle states. True nitrifying bacteria, the autotrophs are aerobic (need O2) and can not form spores, so a bottle on a shelf for months is out of the question. The hetertrophic bacteria on the other hand, can be aerobic, anaerobic (low O2) or facultative (adapt to O2 conditions) and form spores but have very limited nitrification ability….but they can stay in a bottle indefinitely….hence a good shelf life.

    There have been some nitrifying bacteria species developed that do have a limited shelf life and then there are products that actually have live bacteria but are expensive and need refrigeration. Most bottled though are snake oils………..






    Graham Hawkins
    2/5/2001/edited 10/2009/edited 04/2010
    5000 gallon koi pond, 2500 & 750 gallon holding tanks,

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    Well done , Graham .

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    Thanks Todd
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    Graham

    I have a 135 gallon, with some fronts, i have had them for months with out issue, but within the last few weeks, after some water changes, {i am on a well} i noticed some gasping or rapid breathing. I have done water after water change, as i thought the cycle crashed or something, ammonia levels read very low any thoughts???, i even added more mulm from another tank to see if that helped, could it be the water from the well. I appreciate it is just a guess but wondered if you have experienced any like this????

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    Click here to enlarge Originally Posted by kansei
    Well done , Graham .
    agreed

    +1

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    Click here to enlarge Originally Posted by rk1000
    Graham

    I have a 135 gallon, with some fronts, i have had them for months with out issue, but within the last few weeks, after some water changes, {i am on a well} i noticed some gasping or rapid breathing. I have done water after water change, as i thought the cycle crashed or something, ammonia levels read very low any thoughts???, i even added more mulm from another tank to see if that helped, could it be the water from the well. I appreciate it is just a guess but wondered if you have experienced any like this????
    Unless you really did something to the bio-media it's not that. Water from a well has really low O2 levels and generally high CO2 resulting in low pH. A large enough water chnage might give the symptoms that you're seeing
    5000 gallon koi pond, 2500 & 750 gallon holding tanks,

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    Click here to enlarge Originally Posted by Graham
    Click here to enlarge Originally Posted by rk1000
    Graham

    I have a 135 gallon, with some fronts, i have had them for months with out issue, but within the last few weeks, after some water changes, {i am on a well} i noticed some gasping or rapid breathing. I have done water after water change, as i thought the cycle crashed or something, ammonia levels read very low any thoughts???, i even added more mulm from another tank to see if that helped, could it be the water from the well. I appreciate it is just a guess but wondered if you have experienced any like this????
    Unless you really did something to the bio-media it's not that. Water from a well has really low O2 levels and generally high CO2 resulting in low pH. A large enough water chnage might give the symptoms that you're seeing
    I am also on a well, and had these same issues a while back.
    since then more 25%'s and less 50%
    plus added a massive airstone to the back of the tank.. shes on bust.

    Since then I havent had that issue
    "Fish recognize a bad leader." Conan O'Brien

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    yes it happened after a large water change, so maybe that is the issue, thanks

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    hope that helps...

    I know a water change once a week compared to once every other week, well .... is a pain, but again...


    will help.
    "Fish recognize a bad leader." Conan O'Brien

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    One of the 1st courses that I took was 2 day lab from given by the Vets at the U of Fl. Part of the lab was doing diagnostic work from thier actual cases. One was where a koi hobbyist was doing really large water chnages on a 6' deep pond. Everytime he did he'd loose a fish or 2 or the fish would be bleeding from the gills. Everything checked out....

    When they finally did..... and we did too after some thinking...the water was heavily saturated with dissolved CO2 and the fish were absorbing it. When it started to come out of saturation it was rupturing blood vessels....the fish had the bends just like a diver.

    Splash water into a tank
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    Hey Graham, Thanks.

    Really. One part of this site that I truly do enjoy is not just reading all types of new information ~ but getting to know the people who actually do the work.. You can tell a lot about a person by what they add.

    I enjoyed the read, and learned a lot. (may have had to take a break or two in between)
    "Fish recognize a bad leader." Conan O'Brien

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    I just wanted to say this is some very usefull information, esp for a new fish owner.

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    Click here to enlarge Originally Posted by pHasta
    I just wanted to say this is some very usefull information, esp for a new fish owner.
    Great...welcome to the board
    5000 gallon koi pond, 2500 & 750 gallon holding tanks,

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    Bump for a great read

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    Excellent read, thanks!

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    Good information thanks graham i may have to read this couple times.

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