I moved my waterfall Skippy filter water line last summer, after my line break in January draining my pond down to the pump (thank goodness on top of a milk crate!), and pretty sure that line is frozen where it goes up underground on the edge of the waterfall. Everything else is thawed out. Bog is frozen solid on koi pond, too, because that line has some type of clog problem, already had that issue last late fall/early winter, so unplugged it. Thinking junk got into the lines (I would pull the filter and basket from skimmer, without shutting down the pump, stupid me!), and even though I have a clean out, it was still barely running. Pump seems to be fine when unhooked from that line. Sooo ... neither types of filtering can be started up on the koi pond, not good, since that pond is getting lots of green growing. Not too worried, but would like to have at least the waterfall running again. Will keep trying each evening, in case the sun warms up the soil enough to thaw it out.
Even with the 56 degree temps yesterday, my koi are still staying on the bottom of the pond, hiding under the "garages". I saw Lucy, and 2 or 3 of the others, but there are about 15 koi in there, all hiding really well! Goldfish are out and about, most not hiding thank goodness, cause I needed a "fish fix" yesterday! Tried looking several times yesterday and today for the koi, since sun shining so nicely, but no go. Will just have to wait!