One method I’ve been using, with great success, is to get a sieve with holes big enough to let daphnia and micro bugs through but will stop larger inverts like adult shrimps, water lice and nymphs. Pour pond water through the sieve into another container and then pour the contents of that container into the brine shrimp net. Hey presto – a net full of tiny water invertebrates. Obviously the more water you process in this method the more inverts you’ll end up with. The only annoyance is that sometimes very small leeches get through but they can easily be plucked out with tweezers.
Another annoyance is hydra, which are prolific in my daphnia tubs – unfortunately they like to eat daphnia, which is annoying if you only have a few to start your culture. I tend to have hydra squashing sessions when the mood takes me….