Thanks Gazza,this is my 1 st Winter with Koi,I had a look this morning and some of them came cruising from under the bubble wrap to say hello,looking remarkably well,then they cruised back under.The bubble is defintely kicking in now and the difference in the temp between ponds is staying +3 on the Bubble pond.
All the heavy building stuff came this morning for the new Koi pond, the OAP constructor said he would rather be working than sitting in this weather -- I cannot agree on that score

I have to decide on the Butyl liner now.I thought there was only one type when we built the other Koi pond,but it seems there are different qualities.
Can anyone recommend a filter for a raised pond, 50 inches deep and about 1200 -1400 gallons.There will be place behind the top end to bury the filter if necessary.I tend to buy the smaller fish and grown them on,also I use a lot of floating plants.I saw a 10,000 Fishmate filter yesterday for sale in a local water/garden centre at £99,reduced from £225....that was a pressurised one.Also what sort of skimmer do I need/if I need? as there will be no bottom drain.The pond I already have the Koi in has an Oasis filter and that pond has a large waterfall,whereas the new pond will only have small fountain type + airstones.
Sorry to be asking so many questions,you all seem so knowledgeable.I do appreciate your time.
Thankyou.