Is that a "yes" or "no"....

grynning...

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john burton
Bach 50B3
Bass Trombone, Charleston NeoPhonic Orchestra
South Charleston, West Virginia

"Sam Hopkins" wrote in message
.. .
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)
Nitrospira 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 7.2-8.0.
The optimum pH range for Nitrospira is between 7.4-8.2
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. Nitrospira is more strongly affected by
low
DO than NITROSOMONAS.


"O3raledale" wrote in message
...
Hello all,
Currently my pond temp. has dropped to 50 deg. Would now be the correct
time to
shut down my bio-filter/ falls for the winter? Or should I wait as the
weather
may yet again get warmer and heat the pond above 50 deg. again?
Thanks,
Pat