I'm not sure if the micro-organism population in your half-barrel is excessive, but it may be "out of balance" if there are no predatory micro-organisms in the barrel. Try inoculating your half-barrel with a some water from a nearby natural pond. It doesn't have to be a lot of water and you can visually see and remove mosquito eggs or larvae, and you use B.t. anyway.
Of course, the micro-organism population will crash of its own accord as Winter advances.
Mosquito fish might work as well. In small ponds, they are often replenished with new stock each Spring.
Of course, the micro-organism population will crash of its own accord as Winter advances.
Mosquito fish might work as well. In small ponds, they are often replenished with new stock each Spring.
