Originally Posted by
Flower
http:///forum/post/3293535
The book quote is hard to understand for me…There is a temp mentioned (27,2ºC) I read that under certain degrees bacteria can’t grow because it is too cold. The ammonia is not inhibited and will overcome the bacteria colony and it will die off. From what I read it had more to do with temperature than ammonia count.
Yep, there is little chance that ammonia alone will cause the cycle to crash here is another source that gives a strait answer.
Nitrifying Bacteria Facts, by Fritz Industries
Biological Data
There are several species of Nitrosomonas and Nitrobacter bacteria and many strains among those species. Most of this information can be applied to species of Nitrosomonas and Nitrobacter in general., however, each strain may have specific tolerances to environmental factors and nutriment preferences not shared by other, very closely related, strains. The information presented here applies specifically to those strains being cultivated by Fritz Industries, Inc.
Temperature
The temperature for optimum growth of nitrifying bacteria is between 77-86° F (25-30° C).
Growth rate is decreased by 50% at 64° F (18° C).
Growth rate is decreased by 75% at 46-50° F.
No activity will occur at 39° F (4° C)
Nitrifying bacteria will die at 32° F (0° C).
Nitrifying bacteria will die at 120° F (49° C)
Nitrobacter is less tolerant of low temperatures than Nitrosomonas. In cold water systems, care must be taken to monitor the accumulation of nitrites.
pH
The optimum pH range for Nitrosomonas is between 7.8-8.0.
The optimum pH range for Nitrobacter is between 7.3-7.5
Nitrobacter will grow more slowly at the high pH levels typical of marine aquaria and preferred by African Rift Lake Cichlids. Initial high nitrite concentrations may exist. At pH levels below 7.0, Nitrosomonas will grow more slowly and increases in ammonia may become evident. Nitrosomonas growth is inhibited at a pH of 6.5. All nitrification is inhibited if the pH drops to 6.0 or less. Care must be taken to monitor ammonia if the pH begins to drop close to 6.5. At this pH almost all of the ammonia present in the water will be in the mildly toxic, ionized NH3+ state.
Dissolved Oxygen
Maximum nitrification rates will exist if dissolved oxygen (DO) levels exceed 80% saturation. Nitrification will not occur if DO concentrations drop to 2.0 mg/l (ppm) or less. Nitrobacter is more strongly affected by low DO than NITROSOMONAS.
Salinity
The nitrifying bacteria in Fritz-Zyme #7 will grow in salinities ranging between 0 to 6 ppt (parts per thousand) (specific gravity between 1.0000-1.0038).
The nitrifying bacteria in Fritz-Zyme #9 will grow in salinities ranging from 6 up to 44 ppt. (specific gravity between 1.0038-1.0329).
Adaptation to different salinities may involve a lag time of 1-3 days before exponential growth begins.
Light
Nitrifying bacteria are photosensitive, especially to blue and ultraviolet light. After they have colonized a surface this light poses no problem. During the first 3 or 4 days many of the cells may be suspended in the water column. Specialized bulbs in reef aquaria that emit UV or near UV light should remain off during this time. Regular aquarium lighting has no appreciable negative effect.
Chlorine and Chloramines
Before adding bacteria or fish to any aquarium or system, all chlorine must be completely neutralized. Residual chlorine or chloramines will kill Fritz-Zyme bacteria and fish.
Most US cities now treat their drinking water with chloramines. Chloramines are more stable than chlorine. It is advisable to test for chlorine with an inexpensive test kit. If you are unsure whether your water has been treated with chloramine, test for ammonia after neutralizing the chlorine. You can also call your local water treatment facility.
The type of chloramines formed is dependent on pH. Most of it exists as either monochloramine (NH2Cl) or dichloramine (NHCl2). They are made by adding ammonia to chlorinated water. Commercial chlorine reducing chemicals, such as sodium thiosulfate (Na2S2O2) break the chlorine:ammonia bond. Chlorine (Cl) is reduced to harmless chloride (Cl- ) ion. Since dichloramine has two chlorine molecules, a double dose of a chlorine remover, such as sodium thiosulfate, is recommended.
Each molecule of chloramine that is reduced will produce one molecule of ammonia. If the chloramine concentration is 2 ppm then your aquarium or system will start out with 2 ppm of ammonia. Chlorine Remover will reduce up to 2 ppm of chlorine at recommended dosages. During the warmer months chlorine levels may exceed 2 ppm. A double dose would be required to effectively eliminate the excess chlorine.