Low winter pond temperatures

[Duncan]

well as experiments go this was a good one but did not go as i wanted it to

i left the covers on this year but let the temps drop to 8c and only interveined when it dropped below this

most of the fish are fine but i have lost two fish a not so good omosako shiro but a spectacular yamatoya kohaku all these have checked out with no warning and a aeromonas infection on the under side of the tummy

ah well will have to rethink this these are the first i have lost i years through a winter and its not over yet

dunc

[boogatee]

Dunc, what age were these Koi?

[Duncan]

Chris

the omosako was around 5 years old but never grew and the sumi was still underlying



the yamatoya did grow and was spectacular and was three years old from the top it looked great but underneith it was red and sore of course this is the problem when running covers with just a small viewing hatch

gotta run now clean the chickens out

dunc

[tomy2ponds]

HI Duncan I had a discussion with Mark Davis about weather to cover my unheated ponds or not this year,and mark said why are you covering ? I said to stop the pond from getting too cold,He said you will only save a degree or two and that I would be better off not covering and being able to see the Koi and that he did not expect me to loose any Koi providing the koi went into winter healthy parasite free and my water was spot on and kept that way through winter.So I did not cover my ponds went down to 3 GD all koi were fine I had one that developed a 50 P size patch of raised scales on it's side possibly a knock so put this into my QT ran a course of CT and the Koi is fit and well.I except the fact that I am just out side London the weather is not so cold as up north.just thought I would share my winter experience.Normally I cover from Nov to the end of march.Mark also told me he has left 100 Koi out in a mud pond that has frozen over thick enough to skate on,I asked do you expect to loose many of them ? he said we have no acceptable mortality rate and expects all of then to survive the winter give or take a couple.

[welsh_kai_boy]

My pond is raised and i lost 3 koi this year including an 18" kohaku. all the fish were fine last year in a fifth of the water but were covered (200G Vs 1000G). all the fish looked perfect and i am religous in the water changes, if the fish look hungary i feed and the sturgeon are also fed regular small doses of food.

i too had a massive slab of ice on top apart from the spaces left by the filter return and 5 airstones. i dont have a temp gauge on the pond but -8 at night is very cold so my guess is wind chill on larger surface area of water and no covers was a big issue for me.

i have now removed the tarp cover i had on the pond as it is a little warmer now.

my neighbours pond is 2foot deep, green water but sunken and they had no losses ( not the best filter setup either). everyones location and setup is different.

[Gazza]

Hi Dunc,

What a shame mate

What temprature was these normally kept at and do you think it was from sitting on the bottom

[StuW]

Sorry to hear that Duncan, been thinking about this today and I was wondering if it could have something to do with the way we lower temps, ie when we let it cool naturally it occurs over a longer period (even though there is more fluctuation) whereas when we have more control we probably lower it over a much quicker period (with less fluctuation) giving the fish less time to aclimatise to the temp change. I also wonder (like somebody else mentioned) if it has a lot to do with how fish have been treated over previous winters.

[Duncan]

i think the problem lies in the fact, many of these fish i have owned since 2000 and have never seen temps below 15c till this winter but like everyone im trying to save a couple of bob

and coupled to this i only have a small viewing flap in the cover around 3ftx3ft what this does is allows you to view but only from the top and these two fish looked great from the top

so clearly some lessons to be learned here if im going to ride the wintert out let ride it out properly and be able to see the fish

dunc

[markam]

Hi Duncan, where the fish/pond treated with/for anything prior to you dropping temps? Say 1-2 months before winter?

Mark

[markam]

Just noticed on one of your other posts that you had issues with your boiler? Did this cause spikes or dips in your temps?
You also mentioned that you stopped cleaning your filter could this have caused a build of nasties??

Mark

[eds]

I'm not going to jinx this at the moment by posting my experiences unheated this winter but will do later when the pond warms up and I'm feeling 100% confident they're ok!

[madmole]

This year I didnt cover the pond and have had far fewer problems. I did however use my heating to slow the drop to a steady 1C a week and bottomed out at 6C. Fsh have stayed active and still eating

Originally I had about 400W of heating on the 10,000litres just to prevent freezing. I leave waterfall and air on all year as well as the trickle tower. I then added another 1.5KW of heating

First year heated, I covered, I had bad ulcers and put this down to either the fish hitting the wooden frame (It was too low) and or condensation from the frame running down the tannelised wood into the pond.

Second year heated I used Bubble wrap on a suspended frame. Was a pain as the frame collapsed in the snow and when windy. Still had one 60cm fish with bad dropsy in the spring (Virasure and chloramine got him back when I turned the heating up)

I think personally the lack of seeing the fish is preventing seeing problems early and the lack or light may be an issue. Also concerned about condensation running into pond from the plastics used. Of course this has to be offset against the extra cost due to heat loss

So for me from now on I will go back to using the heaters to stabilise heat drops and rises and preventing freezing in the winter. Also to minimise time between 12 and 16 Degs C and maximie summer heat at >18C

[Thorny]

My second year unheated and uncovered, Koi seem much happiers this year compared to last. I think I can count on one hand the days I have been down to them to find them sat on the bottom. They are usually swimming around and even come up to look for food. The trouble I found last year and the end result was a lost Showa was the warming of the pond rather than the long cold period. So this year as the water was up to 9.5 degrees last week I flicked the heater on to hold them at that temperature, as I think the unsettled period did for the showa last year. So I will bring it up with mother nature now just to get them settled above 13 degrees rather than up and down like last year.
Justin

[Dave Collins]

I'm heated and covered, pond has been held at +10°C since 22 December. I will leave temperature and covers until mid March but am always guided by the ambient temperatures. Once the covers come off then I will start a course of Virkon S Aquatic to lower bacterial count while raising the temperature.

I like to get to +16°C fairly quickly and then follow the ambient temperatures upwards with the heat pump. During winter I feed once or twice a week but don’t start the summer feeding program until the pond has been at +18°C or more for 4 weeks, this lets the filter catch up.

Maybe next winter I will try dropping to +8 or 9°C, not sure it would be too much cheaper though.