24
During acclimation, the backwash frequency of your
PolyGeyser
® filter should be 1-2 backwashes per
day. This will keep the bead mixed and promote homogenous growth of nitrifying bacteria throughout
the bead bed.
Figure 4 illustrates the classical pattern of TAN (total ammonia nitrogen) and nitrite concentrations
observed during filter acclimation with animals. The process starts with an accumulation of TAN. For a
week of two the TAN concentration will steadily increase, then suddenly (typically within 36 hours) the
Tan concentration will suddenly drop to near zero levels. This indicates that the AOBs responsible for
ammonia conversion to nitrite are present in large numbers. At the same time there will be a sudden
rise in nitrite levels, followed by a gradual increase which will continue until suddenly the second group
of bacteria, Nitrobacter, catch up with their new food supply and the nitrite concentrations plummet.
The filter is now considered acclimated to a light loading. This initial stage of acclimation is critical
because during this period populations of bacteria which can effectively attack the specific waste
produced by the animals become established and these bacterial populations adjust to operate under
the water quality conditions and temperature regime found in your system. This unique culture of
bacteria will remain in the biofilter for years if maintained.
Table 3 summarizes things you can do to accelerate the initial acclimation of the bead filter. These
procedures can reduce acclimation time to as little as two weeks in a warm freshwater system. One of
the principal limitations of acclimating a filter with animals is that little or no nitrite is available for the
growth of NOBs until the AOB population has become established. This means that the very slow
growing Nitrobacter cannot even get started for over a week. Therefore, you can simply reduce the
acclimation time by adding nitrite at the start.
TAN and Nitrite Concentrations
0
1
2
3
4
5
6
0
10
20
30
40
Days
C
o
n
ce
n
tr
a
ti
o
n
[
m
g
/l
]
TAN [mg/l]
Nitrite [mg/l]
Initial Acclimation
Loading Increase
Figure 4. Tan and nitrite concentration build-ups are normally observed during the initial acclimation
of a biofilter.