OK, so on that basis you cannot be changing a lot of water in the pond (I'm not cheating just looking at the readings). Your filters are using up the carbonates as part of their process.
Is that a problem re: burn KH? Not with that high KH reading - you have loads of spare "buffer" KH.
Is the lack of new water affecting the health of the koi? Well that's the huge debate. One I can't answer myself.
It's worth checking your source water regularly.All water companies in Britain are abstracting an increasing amount of water from rivers, rather than underground aquifers, meaning the water is softer than it can be/has been.
Ahh the good ol' water companys lets not go down that road
thanks for your coments guys I havent vetured out side yet cos its so foul out there and I gave my self a good english weather cold yesterday from getting wet doing my filters.
I'll let you know what I find later on .
