Oh man, my buddy had the exact same thing happen with his rain barrel in Seattle! He left it open for like two weeks and it turned into this gross soup of wigglers, he said it was nasty. What he ended up doing was cutting a piece of window screen and rubber banding it over the top, plus he drops in one of those mosquito dunk things every month or so. Seems to have worked for him so far, but your mileage may vary depending on how hot it gets where you are. Cheap fix though, way better than dumping the whole thing out every few weeks.

Ugh, those peat pellets are a trap! I had the same problem with mine getting moldy, they hold water like crazy. Your neighbor's plain pot idea is the way to go, basil honestly just wants dirt and sun. Cheap soil wins every time.

Man, I used to roll my eyes at the "you get what you pay for" crowd too, then my $150 pad started leaking at a seam on night two of a trip and I spent the rest of the weekend on cold ground. From what I've seen it's mostly the seams and valves, the cheap ones either weld them right or they don't, and price does not always tell you which. So yeah, I've come around to the idea that a test on your floor at home before you trust it in the woods matters more than the price tag.