making your own is good because you have control over what goes in it. it's also great when making up large batches. always nice to have extra rather than not enough. as far as insects go, if you can purchase a culture locally, that is the way to go. otherwise order some online, or buy some from another member here. then you can either culture them out of the tank (preferred) or in the tank. either way, it doesn't matter. but either way, give them a few weeks before adding the predators. they will snack on your critters in between meals, so it's best to give them a fighting chance.