Thread: Winter heating quandry

Good morning,

I hope your all well,

I am currently running the pond at 15c fish fine eating and active etc, i am in two minds wether to maintain this temp throughout winter or to turn off the ashp and let the ambient temps do what they please...... my stupid overthinking brain says no keep them warm as they have never been below 14c before as i worry that they might suffer if getting down to say 6c as they have never experienced this before, if i turn off the heat now and looking at next weeks ambient temps the pond will fall roughly a degree in 24/48 hours as temps between 5 - 8c for the week? so pond could go from 15c to say 8c within a week to ten days? is that too much of a drop to quickly ? any thoughts / views appreciated..... then on the other hand i have read articles where its deemed good pratice to allow your fish to over winter heatless... thanks Steve

I think with the current energy costs, there is more reason than ever to question the temp your paying to maintain and whether it is worth it.
What is your aim with heating to 15C? Its too low for feeding for growth. It’s a touch low for full immune system function. It’s high enough for parasites to multiply though if there are any around.

If you do decide to reduce your temperature, I would advise doing it gradually. Reduce the thermostat by 1C every 3-4 days until it gets down to whatever temperature you choose.

I’m currently not heating my pond like I usually would at this time of year- I heat to 23C through to the end of august to keep feeding heavily, then slowly decrease it down in November and December. This year the pond is covered and has slowly fallen and is now at 12C unheated.
I would personally heat if it falls below 8C as I hate to see miserable fish hanging out on the bottom (and I can see their little miserable faces through the pond window from inside the house ).

I tend to think of heating as having zones for different purposes:

• To feed for growth (optimal growth is over 20C, if you overfeed below this you might find fish use it to get fat not bigger)
• To reach the right temperature for a medication- some require min 16C to use them.
• To prevent fish suffering from the cold- our ponds don’t have temperature stratification like a natural lake due to pumps turning over the water and mixing it. The minimum temp any wild fish would experience would be around 4C. Koi are less hardy than their wild counterparts so I believe even 4C is too cold. You will have to decide for yourself whether you believe in keeping the pond out of ‘aeromonas alley’. I’ve kept my pond at 8-10C for a while in previous years and never had an issue with that, but your pond might vary.

First winter with an ASHP - so much conflicting advice around. I am covered and maintaining 16C until Christmas. Plan is to drop by 0.5C a day until I reach ambient temperature (4/5C) and then wait until the beginning of March and slowly raise back up to 16C.

10 month 'summer' and 2 months 'winter' to help cleanse the pond and help reduce any parasites/ bacteria.

Will see how that goes - and how the fish react.

Good evening,
thanks for your replies......

Having thought more on the matter today and reading your replies i will start to reduce gradually, with 8c being the lowest target, thanks Steve and Feline.....good luck Stormstorr with your winter plans....

My pond which is uninsulated, uncovered and fully in ground is now at about 8C.
Being in "thermal contact" with the subsoil means that it will go down to about 6-7C and stay there unless we get a very cold snap.
If it goes below 5.5C I have simple 2.4kW (81p/hr) electric heating.
Last year the heating was on for about 12hrs in total through the Winter.
The most relevant point here is that at these low temperatures the fish do lie on the bottom most of the time (no window so only see this if I look) and slow right down when they do swim.
I try and avoid anthropomorphising their behaviour and demeanor - easier to avoid guilt pangs that way.
However, my last pond had no heating at all and I kept koi like that without related issues for over 20 years.

Originally Posted by smartin

Good morning,

I hope your all well,

I am currently running the pond at 15c fish fine eating and active etc, i am in two minds wether to maintain this temp throughout winter or to turn off the ashp and let the ambient temps do what they please...... my stupid overthinking brain says no keep them warm as they have never been below 14c before as i worry that they might suffer if getting down to say 6c as they have never experienced this before, if i turn off the heat now and looking at next weeks ambient temps the pond will fall roughly a degree in 24/48 hours as temps between 5 - 8c for the week? so pond could go from 15c to say 8c within a week to ten days? is that too much of a drop to quickly ? any thoughts / views appreciated..... then on the other hand i have read articles where its deemed good pratice to allow your fish to over winter heatless... thanks Steve

i'd just play it by ear mate,
see how the fish are as you lower temperatures.

my heating is set to 13C at the moment, but the pond is still at 15.5C no heating on for the last couple of weeks.
i'm just setting it as a back stop if we have a cold snap. and temps plunge.

but i would probably leave the window cover on if it got down to 8C and hold it there,
but mine didn't go any lower than 12C with no heating last year...