[abbeyline]

Thanks bcfc. All these points covered. Except the scope PS Whats kh?

[bcfc]

kh= carbonates. its wot ur filter uses up out of the water. so if ur filter uses all the carbonates in the water, u will have a ph crash. = dead koi. so i would get a api kh test about a £5 i need to get one myself has mine is running out. and has bandit asked? do u have air going into ur pond???????????????

[abbeyline]

Reference my sick fish. Well I had the water tested. All fine. No parisites. I'm thinking they have an upset tummy after feeding them when the water was too cold. They have not been fed for a week now and seem to be getting better. Has anyone had this problem and is there a remedy? Apart from not feeding again when the water is too cold.

[miles41]

I personally haven't experienced this. I don't feed at all if my koi aren't up and actively seeking food & attention, and this can be several months over the winter (say Nov to March).
Just keep an eye on them and you'll know if they're happy or not.
Good luck with them.

[miles41]

ps. check your water temp and be very cautious about feeding below 10°c.
I check mine very regulary and at about 13°c now; as it fluctuates quite a bit at this time of year.