OK, so flood and drain is all right during the spring, summer, and fall, when it's not ridiculously cold, but when it doesn't get out of the mid-30's for days on end, and it gets below 20 every night for a week, flood and drain with an outdoor pond is not smart!
Checked on things this morning, and it appears that my aerator, though powerful enough for my pond, is not powerful enough to keep the whole damn thing from freezing over! I had 1-2" thick ice covering the entire pond, so my pond pump wasn't getting enough water to send through the system, which then caused my return line to freeze, too.
I'm just hoping that the return line doesn't crack or burst when it thaws out.
Assuming it doesn't, I'm gonna switch the pump to run 24/7, which worked last year to keep the pond ice-free for the duration of the winter, which was also quite cold. Continuous flow for the cold season.
I wondered if this was going to happen, and I now I know.
I've got the pump off today, which means that the plants won't get any water. I'm just hoping the plants survive the day while I'm at work. I'm hoping to put some water into the pond today, which should warm it up a bit, and get that pump going full steam.
BTW - putting your hands into icy pond water repeatedly to try and get the pump to go sucks when it's 18 degrees out.
2-3 days have now passed since this post, and despite day time temperatures climbing above freezing all three days, the grow beds are quite literally frozen solid. I've removed the greenhouses from above them, hoping that the rain we're getting now will be able to penetrate into the hydroton and help to thaw it out. Tomorrow, it's supposed to rain and reach the upper 40's. With any luck, everything will thaw out and the return lines will drain. If that happens, I'll be able to turn everything back on. Even if that does happen, I wonder if the plants are still alive, as their roots are quick literally frozen into a block of ice right now. Should be interesting!
UPDATE 12/12 -
Got 2 out of the 3 growbeds going again. The 3rd is still frozen in the return line. The arugula there doesn't look it will make it. Many of the leaves look translucent, as if all the chlorophyll has abandoned the plant. Nevertheless, I'd still like to get the flow going again, though it's supposed to be even colder tomorrow night than it was last week. Based on last year, though, as long as the water was flowing, it never completely froze over or through, and everything was still working. We'll see...
Cascading Flood & Drain Gutterbed
1 week ago