Well…The weather is now in the lower 40˚F
(4.44˚C) in Chicagoland and it will be dipping into the upper 30˚F (-1.11˚C) next
week and for conventional filters this is that time of year that most pond
owners once again worry about their nitrogen cycle.
QUOTE:
“Temperatures like this are very bacteria
unfriendly and the temperature for optimum growth of nitrifying bacteria is
between 77-86° F (25-30° C) seldom is this temperature reached in the
springtime and at this time of the year it will only get worse not better.
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.”
QUOTE: From Dave Collins in France.
"Hi Brian,
As you know I only have an Anoxic filter with a
drum before it. It’s been running for three and a half years and depending on
feeding levels the nitrate hovers around 6mg/l.
So you'll no doubt be surprised with my answer
but I would keep the bead filter. As you say, if it’s not broken ……… The bead
does work against the Anoxic but your Anoxic is large enough to cope and gives
you peace of mind.
What I say is, sit back and enjoy a glass of
whatever takes your fancy and watch your Koi swimming in clean clear water."
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 because of 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 U.S.A.
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.
Cheers,
Kevin
