Nitrobacter and cold weather:
One of the most important
and least understood, aspects of successful pond keeping is biological
filtration and its function in the nitrogen cycle. Species of Nitrosomonas and
Nitrobacter nitrifying bacteria are classified as obligate chemolithotrophs and
are gram-negative microbes. This means if you use a gram-negative inhibitory
chemical to treat an infection on your Koi, so will it also kill off the
beneficial bacteria in the process. They are obligate aerobes and cannot
multiply or convert ammonia or nitrites in the absence of oxygen, unlike
facultative anaerobic bacteria that can.
Nitrifying bacteria have
extensive generation times due to the low energy yield from their oxidation
reactions. Since little energy is produced from these reactions they have
evolved to become extremely efficient at converting ammonia into nitrite and
then again into nitrate. Most of their energy production, which is over
seventy-five percent, is devoted to fixing CO2 via the Calvin cycle and very small amounts of that energy remain for
reproduction and growth. Nitrifying bacteria reproduce by binary division and
as a consequence, they have a very slow reproductive rate.
Under optimal conditions
(which by the way would be in a lab and not in our ponds), Nitrobacter may
double every 13 hours. More reasonably speaking though, they will double every
24 hours in our ponds. This is an extremely long time, considering that heterotrophic
bacteria can double in as short of a time as 20-minutes, exceeding 35-trillion
cells in that time. Now you see why in natural systems and waterways they use
and depend on heterotrophs over autotrophs. Faster reproductive times and less
stress on the entire eco-system.
They have a complex
cytomembrane that is surrounded by a slime matrix (also known as a polymeric
adhesive) and therefore they (Nitrobacteraceae) are unable to form
spores. All species have a limited tolerance range and are individually
sensitive to pH, dissolved oxygen levels, salt levels, temperature, and
chemical insults. In our ponds, which are closed systems; they can survive
short periods of adverse conditions by utilizing stored materials within the
cell. When these materials are depleted, the bacteria die. They do not have the
ability to use other sources for their carbon needs. They can be as sort lived,
as 24-48 hours, and if conditions are impertinently unsound this timeframe can
be shorten by those veritable insults. However, the Nitrobacter bacteria strain
may have specific tolerances to environmental factors and nutriment preferences
not shared by other, very closely related strains, which there are several
species and many strains among those species.
The temperature for
optimum growth of nitrifying bacteria is between 77-86° F (25-30° C) seldom is this temperature
reached in the springtime. On top of that, this temperature is considered too
high for Koi and Goldfish and is not consider optimal for such. Growth rate is
decreased by 50% at 64° F (18°
C) and will decrease even more by 75% at 46-50° F. The worst part of this is that at 39° F (4°
C) no activity will occur at all and nitrifying bacteria will die at 32° F (0° C). Nitrobacter is less tolerant
of low temperatures than Nitrosomonas. In cold water systems, which our ponds
are in late winter and early spring, care must be taken to monitor the
accumulation of nitrites. Not so with the Anoxic system.
Nitrobacter will grow more
slowly at high pH levels (7.8-8.0 most of our ponds in the US fall in this
range do to hard-water) and optimum range is between 7.3-7.5. Care must be
taken to monitor ammonia if the pH begins to drop close to 6.5. At this pH
range, almost all of the ammonia present in the water will be in the mildly
toxic, ionized NH3+ state. Maximum nitrification rates will exist if dissolved oxygen (DO)
levels exceed 80% saturation. This would explain why hobbyist must oxygenate
their ponds too the maximum, not only for the fish sake, but also for the
bacteria as well. Nitrification will not occur if dissolved oxygen
concentrations drop to 2.0 mg/l or ppm (Anoxic conditions,) or less.
Nitrobacter is affected more by low dissolved oxygen than Nitrosomonas.
Also for those hobbyists
that like to add salt to their pond as a prophylactic; adaptation to such
salinities may involve a lag time of 1-3 days before exponential growth begins.
Nitrifying bacteria are also photosensitive, especially to blue (750k) and
ultraviolet light. After they have colonized a surface this UV light poses very
little problems for them afterwards. During the first 3 or 4 days many of the
cells will be suspended in the water column especially after reinoculation of
the pond after a cold winter. Therefore, UV light/germicide lamps should remain
off during this time. Once again this is a very decisive time for our Koi, in
as too eradicate pathogens and germs, and we have our hands tide because of the
bacteria that we are using, not so with my system.
Now let’s take the Anoxic
filtration system and the bacteria that it uses, and compare what has just been
said above. Hobbyist that use this kind of filtration system should start their
filters when temperatures reach 32o F (0o C) or
above and the pond water has become stabilized so as not too incur freezing of
pipes or waterfalls. The
Anoxic Filter is already working without the reinoculation of such chemicals,
bacteria cultures or heterotrophic bacteria spores. This is a very crucial time
for our fish; because of their weaken state from such a long winters rest. As
you can see Nitrosomonas and Nitrobacter are not of much help to us until water
temperatures have risen to a more ideal rang that suits them and not our
animals. I have written quite extensively on this subject on the Internet and in
my Cd-book about bacteria staying active during winter months.
This is why most hobbyists
in the colder parts of the US will not even attempt to get their filters online
until latter in the spring while the ones with the Anoxic Filter have started
their filters in late winter. In fact Koi and pond clubs throughout the Midwest
are telling them not to. After the initial water change and filter cleanout you
will notice that your Koi will become more active earlier than in previous
years. This activity of our Koi happens two to three days after cleanout. They
will actually begin to forage for Algae and worms far earlier in the year (39° F (4° C) than when using conventional
filtration methods. The Algae and worms will not only give our animals beneficial
bacteria that is so badly needed at this time, but will also act as a laxative
from the worms they eat. These natural foods will not only strengthen the Koi’s
immune systems to fight off primary and secondary infection should they acquire
such help. It is not unusual to find Koi swimming around like it’s a warm
summer’s day when pond temperatures are in the low 40o F range.
Yes, you can keep testing
your water until the cows come home but you won’t find any ammonia/ammonium or
Nitrites. Even though the Koi have become active enough to take processed
foods, still all parameters will stay stable without incurring any undue cost
or stress to the animals or the hobbyist.
As you can see by
the photo that was taken in Mach of this year 2009 (Note: The next day after
this picture was taken it snowed in Chicago 3-6”), look how active this
overcrowded 1600-gal (US gallons) pond is. Some of the big girls in this pond
are over 25-29”. (The Asagi 29”, Beni-goi 30”, Sanke 29”, Chagoi 25”) Yes there
are over 50 plus fish in this pond and still no ammonia or nitrites or
nitrates. These fish aren’t lying on the bottom like giant slugs waiting for
the hobbyist to help them; they are already doing what comes natural to them:
Living a Koi’s life! Look how clean the water is, you can see four feet down
and see pieces of gravel that are in the pond.
Using the Anoxic system
you can fire up that UV light / filter immediately and have no adverse effect
on the bacteria, because they are already secured in the biocenosis clarification baskets. It now becomes a win win situation for you and your animals.
Anoxic Filtration Book... Still free
on Apple's iBook store
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