The plants are “yellower” than they were two months ago, and there’s not much in the way of animal (insect and snail) activity. I hope it’s just because of Winter, and not that everything is dying. You’ll note that that sprouty plant – the one with the leaves – has taken over, and the hornwort has died away. The last diving beetle has died; its corpse is stuck in the fuzzy green algae (and not visible in the photo). Also note that a few snails have “suicided” by climbing up the sides and out of the water. Some bits of algae have also crept up the sides. It’s also hard to see, but there are a few bubbles trapped in the mess of algae at the top. They’ve been there since the beginning.…

On the morning of January 21, 2024. The dark spot is a bit of wood that got stuck in the algae.

It’s been suggested that the lifelessness is due to oxygen starvation. It is indeed possible; I’ve had the thing sealed for months. I’ve decided to “pop the top” and leave it unsealed in the hopes that it might recover its vigor.

If not, I’ll just dump it all back in the pond where I got it, and start over.