Tank full of wriggling mosquito larvae. How to kill them?
Can't just dump it out. Putting aside that it weighs half a ton, the whole point of having a tank is to COLLECT the water.
Scoop them out? They squirm and wriggle away. Probably doable anyway, but would take a long time, and I'd end up scooping out half the tank or more, and I still wouldn't get them all.
Strainer? Actually, this never occurred to me. (We don't have the right sort of strainer anyhow.)
Put fish in the tank? I considered it! But the goldfish in our little pond are loaners (they belong to our neighbor) and they're fine where they are. Also, I don't think two goldfish could eat several hundred larvae. Thin the herd, at best. Buy more fish? The nearest pet store is some distance away...