Lethal Ammonia level for bacteria

srfisher17

Active Member
Would someone know the level at which ammonia kills aerobic bacteria? I'm guessing somewhere about 1-1.5ppm. A source would be great too. Yep, this is more of the ''water change during the cycle" argument. Thanks!
 

flower

Well-Known Member

Okay I am not the smartest one on stuff like this but doesn’t the bacteria break down the ammonia? Not the other way around…

Even if you have too much ammonia eventually the bacteria will catch up and neutralize it. A critter can’t stand the conditions long enough for that and die from the ammonia.
 

2quills

Well-Known Member
By killing do you mean will the bacteria die off if the ammonia is to low? If you want to kill it you could always cut of it's oxygen supply since it needs it to survive.
I would think they higher the ammonia...the more bacteria would grow.
 

geoj

Active Member
Factors Affecting Nitrifying Bacteria Growth. By Sergio Chaim
Although there are several nitrifying bacteria populations and species, each one having different environmental requirements, that makes possible set a biofilter for any water condition were fishes are kept, the nitrifiers growth and/or rate of nitrification are in large extent affected by ammonia level, pH, alkalinity, temperature, dissolved oxygen, suspended solids, light and salinity.
Ammonia.
Ammonia is the main bacterial growth limiting factor in aquaculture biofilters. Research has shown that ammonia removal rate raises as function of increasing TAN concentrations up to around 2-2.5 mg/L, when ammonia removal rate reaches a plateau and further increases in effluent TAN do not cause any significant increase in TAN removal rate (Greiner and Timmons, 1998; Kamstra et al. 1998). On the other hand, Zhu and Chen (1999) estimated that for 27,2ºC the mean minimum TAN concentration needed to keep nitrification biofilm at health steady-state is 0.07mg TAN per liter.
So as the Ammonia rises above 2-2.5 mg/L the bacteria removal rate levels off and I have read some where
that up in the thousands ppm the bacteria die off.
 

flower

Well-Known Member
Originally Posted by GeoJ
http:///forum/post/3293485
So as the Ammonia rises above 2-2.5 mg/L the bacteria removal rate levels off and I have read some where
that up in the thousands ppm the bacteria die off.

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.
 

geoj

Active Member
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.
 
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