I'm not a learned head, but I live in Mexico, and at the altitude I live
(1600 m) I've had biological filters working at temperatures below 20 C.
Two things you mentioned are true: it depends on the strain of bacteria and
how exposed they are to abrupt temperature changes. I've had filters in
water that drops to 8C and when the temperature goes up to a whopping 17,
the nitrogenous wastes drop in less than 12 hrs.
Robert
Mexico
At 11:07 PM 11/14/98 +1000, you wrote:
>Yes Bruce you are right, we would have to ask more learned heads for expert
>advice on this one.
>
>Its very difficult to be a learned head on biological filters in cooler
>water here in Queensland. I mean, winter fell on a Thursday this year, and I
>was busy that day.
>
>My very basic understanding is that while dissolved oxygen is increased in
>cooler water, it doesn't have any great effect on the bacteria, which
>function better in the 20s, and apparently physically just don't appreciate
>cooler temperatures. That's in a well maintained system of course, if the
>filter is already a bit anaerobic, an increase in dissolved oxygen at lower
>temperatures could be expected to have more impact.
>
>Whether exactly the same bacterial strains are in filters here in the
>sub-tropics, as are in filters in cool-temperate regions is also something I
>don't know. Andrew may well have bacteria down his way that tolerate cooler
>temperatures better than ours.
>
>You have had me raking through references today, but so far I have not put
>my hands on what I'm after, except for a reference by a Dr David D. Sands,
>of the Aquarian Advisory Service in Britain, that bacterial systems
>generally work better in warmer water, with peak efficiency at 25 degrees C.
>
>I've seen some material fairly recently which suggested that both fish and
>bacteria which were kept in constant water temperatures for lengthy periods,
>(heated tanks) handled drops in water temperature poorly, compared to
>specimens which had experienced regular temperature fluctuations (unheated
>tanks). However I haven't found that again yet.
>
>Maybe some of the NSW/ACT Koi pond keepers would know more. Know any Andrew?
>
>Is there a bacteriologist in the house?
>
>Doug Collom
>
>-----Original Message-----
>From: Bruce Hansen <bhansen at ozemail.com.au>
>To: rainbowfish at pcug.org.au <rainbowfish at pcug.org.au>
>Date: Saturday, 14 November 1998 12:38
>Subject: Re: [RML] Designer Fish
>
>
>>I wonder if that is so Doug - I thought that the big factor in UGF's is
>>aerobic activity and that oxygen dissolves better at cooler temperatures.
>To
>>my mind that would translate into better biological activity when cooler
>>than warmer. I guess there is an optimum temperature range for this process
>>but would have to ask more learned heads for the figures :)
>>
>>
>>Regards,
>>Bruce.
>>
>>Bruce Hansen, A.N.G.F.A., Advancing Australian Aquatics.
>>
>
>
>