• Shrimp Tank Cycling

    Cycling a tank refers to the build up of essential beneficial bacteria in filter and tank, which break down wastes to non-toxics. The implications of this are probably the single most important factor in keeping shrimps alive.

    The ammonia level in a matured tank should be zero. Shrimps tolerate no ammonia, and any ammonia in water causes death to shrimps immediately or over a few days. Ammonia is continuously generated by shrimp and fish waste, rotten food and decaying plant matter, the level of ammonia generated by these sources are usually kept at extremely low and insignificant level in a matured tank with the presence of nitrosococcus bacteria mainly found in a filter biological medium.

    A sudden, temporary and large increase in ammonia level is known as ammonia strike. An ammonia strike can due to unattended dead shrimps or fishes, uses of medication that kills the bacteria, adding of large number of livestocks, overfeeding and over clean a filter. With the increase level of ammonia, Nitrosomas will increase accordingly to work on it and usually takes a few days before ammonia level comes down, in the meantime, shrimps are exposed to ammonia and is detrimental to them and normally resulting in death. The level of bacteria saturates at what the effective surface area of biological medium can offer them to colonised on, so it is alway good to provide a large effective surface, even though most of the time is not used.


    Ammonium ion is oxidised by bacteria to form nitrites:



    NH4+ + 2 H2O = NO2- + 8 H+(ammonia) (water) (nitrite) (hydrogen ions)

    An ammonia strike results in a surge of nitrite level, which is also temporary and the level should subside with building up nitrospira bacteria. Again, over this time, when nitrite level is not zero, shrimps survivals are threatened and often result in death.

    In a matured tank, the nitrite level should be zero. Prolonged exposure to nitrite even at a low level causes shrimp death. Nitrite is further oxidised to nitrate, which is less toxic compare with ammonia and nitrite:



    NO2- + H2O = NO3- + 2H(nitrite) (water) (nitrate) (hydrogen ion)

    It is important to keep the level of nitrate to be 15mg/l or 15ppm or lower. A desirable level will be 5ppm or less. With regular partial water change and help of fast growing plant like frogbits and hornwort, it is possible to achieve 5ppm or lower.

    Personally, I prefer shrimpless or fishless tank cycling, I can cycle the tank with the level of ammonia I want. Furthermore, it is impossible to use shrimp as a source of ammonia, the shrimps will get killed before the tank is matured to bring the ammonia down or the shrimps are not capable of producing enough ammonia in a big tank, and without ammonia, the bacteria will not grow.

    These are needed for tank cycling:



    Ammonium powder, which is ammonium bicarbonate or ammonium carbonate easily available in bakery shop is used as a food for the bacteria.

    Test kits for total ammonia (NH3/4) and nitrite are needed.

    Test kits for nitrate is recommended.



    Fill the tank with aged or anti-chlorinated water, connect the filters and let it runs, keep the temperature at 28C to 32C, lower temperature is fine, but will take a longer time for the whole process. Keep PH about 7.0 which will help in shortening the process. The water has to be well aerated, position your filter output to create water surface move.
    Mix ammonium powder into the tank to achieve concentration of about 10mg/l, use total ammonia test kits to confirm the concentration.

    Starting checking ammonia level at the 14th day, you may see ammonia level dropping from 14th days onwards and increase in nitrite level. It is common not to see the action of beneficial bacteria on the 14th day and some cases it will take up to 21 days before any drop in ammonia level is detected.

    The cycling is completed when the nitrite level drop to zero. I usually wait for 3 more days upon detection of zero nitrite, then do a large water change, change as much as you can so as to remove nitrate from your tank.

    Top up with aged or anti-chlorinate water, decorate the tanks with plants, stone and driftwood, condition the water to the right parameters and you are ready to introduced shrimps.

    You can jump start the cycling by using aged biological filter medium or bottled "bacteria". Even though with the use of these, checking with test kits for ammonia and nitrite level to confirm end of cycling is still necessary.

    Cycling needs time and patience, generally, it takes 21 days to 50 days to complete.

    Keywords: shrimp tank, fishless tank cycle, beneficial bacteria, nitrosococcus, nitrospira biological filter medium, biofilter