Thank you. I understand now...

off to WalMart to buy a thermometer..

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

"Sam Hopkins" wrote in message
.. .
The bacteria will continue to do their job until the water temp reaches 39
degrees. They will pause between 32 and 39. So if your temp is going from
say 35 to 50 I'd leave it on. If it starts staying under 39 you can turn
it
off.

"John Burton" wrote in message
...
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