Effects of Temperature Drop

[Sally]

Hello, I have been reading the posts in this Winterising section and I think I nearly understand how I need to prepare for winter. I’ll get some Wheatgerm food and keep my eye on the water temperature.

I have two questions at this stage if I may.

The weather forecasts are predicting a sudden drop in temperature over the next couple of days, how long does it have to stay cold before the pond water temperature also drops?

When the water temperature drops to close to zero will the fish and plant debris still produce waste and so ammonia and if so at what sort of temperature does the filter bacteria stop working?

Our pond is about 2000lts and about 4 foot deep at the deep end.

Thanks

Sally

 

[addy1]

Filter bacteria stops around 45-50 degrees F.
My pond has been bouncing between 53 F and 65 F we are getting another cold dip, but it bounces back up. At this time I am still feeding the fish wheat germ food. When the temp was near 50ish they did not seem to have any desire to eat.

How fast your pond will change in temperature depends a lot on how it is built. The depth your pond is will help keep it stable in temperature. With my bog I have a lot of surface area that gets cooled or heated dependent on the weather, I also have a 85 foot stream that cools the pond.. Therefore the pond cools faster than if I had just a filter running.

The fish still produce waste it just slows down in production.

Once my pond goes down and stays down I will quit feeding for the winter.

 

[HARO]

Contrary to common belief, nitrobacter and nitrosomonas bacteria do not just stop working when temperatures drop. Ideal temps for them are around 75 to 80 F., at which it takes one bacterium about 13 hours to split, forming two. In your pond they split every 15 to 20 hours. (In the same time, one E. coli bacterium can produce a population of 15 TRILLION cells!) Reproduction is cut by half at around 64 F., and by 75% around 45F., but they remain active until they die, which occurs at the freezing point. By this time you should have stopped all feeding, and your fish would be dormant. John

 

[Sally]

Thanks for the replies. Sorry for the delay in getting back, it’s been a busy weekend!

Addy1 – The pond water temperature varies between 9°C and 11°C (48°F to 52°F) at the moment, whilst the ambient temperature is all over the place from 3°C first thing in the morning to 19°C by late afternoon (37°F – 66°F). The pond is constructed with a 2 foot high wall above ground and dug down 2 foot deep into the ground so there will be some heat loss through the wall but its 8 inch concrete block so it won’t be too bad. The fish are still swimming at all levels and eating well.

Haro – So a linear relationship between temperature and bacteria reproduction rather than a sudden drop off. Interesting E Coli figures!

I’ll feed until they’re not interested and turn off the filter when the water temperature drops to consistently below 3°C or 4°C. I’ll have to shut down the cascade output from the filter before then.

Thanks again.

Sally

 

[sissy]

just make sure you scoop out uneaten food .