Answer taken from a Koi forum by Manky S.
Thanks for the opportunity to use my favorite expression "the dimorphic metabolism of facultative chemo-litho-autotrophs” (1) and this time it's actually relevant rather than being crowbarred in just to show off!!
Anyway, if I understand correctly you are planning to avoid the bugs in the baskets from going dormant over winter in an anoxic pond by transferring some of the baskets to a heated grow-on-tank. [Ed: This is a very common practice here in the US by hobbyists, especially those that winter-out their Goldfish. They have a separate tank and then through a sump add some of the BCB’s to the sump and walla, instant filter ready to go far wintering-out your pets with no cycling time involved.]
This is Brian’s finished MKII Anoxic Filter with all BCB’s in place with plants in some of them. Just pullout some of the BCB’s that you need for your fish tanks and your done, instant biological filter.
If that's so then no problem (ish).
The bugs in the baskets are just like the biofilter bugs that we are used to. Their activity is very much controlled by their ambient temperature so, as the water temperature falls, they use less of whatever nutrients they rely on.
Transferring them from water that is beginning to go cold into water that will be kept warm over winter will allow them to stay active so the idea will be successful (ish).
Their metabolism and respiration is as described above and means that there are two points to take into account.
"Facultative anaerobic" means that they prefer to use oxygen when it's available but switch to stealing oxygen from nitrate (or phosphate) when the level of oxygen in their environment falls to about 1 mg/L to 2 mg/L. Also their metabolism is "dimorphic" which means that it has two distinct phases i.e. it switches from one nutrient to another.
When you first submerge a basket in pond water, aerated water floods in. After a time bug respiration will have used enough oxygen so that the level will have fallen to around 1 mg/L to 2 mg/L. It won't go any lower because that's when the bugs switch to obtaining oxygen from nitrate so the oxygen level in the basket will permanently stay at that level.
So far so good! Now we have them doing what we want them to.
If you take a matured basket out of water, the oxygen-depleted water in it will drain out. Then when you put the basket back, aerated water will flood in and the anoxic environment will be gone.
I don't want to overstate the case because the anoxic situation will return but their facultative thingy will be interrupted until it does. So if you mess around with the baskets too often there will be more interruptions than normal activity.
So that's where some understanding comes in, I don't see any problem making this change over from unheated to heated and back again once a year just as long as you remember what will be happening each time you do.
I hope that isn't too complicated but "yes-no" answers aren't always possible in the microbiology world.
(1) [Ed: Chemoautotrophic is a bacterium that derives its energy from the oxidation of inorganic compounds.]