Hi there.

I use something that's called a "turkey baster" It's like a very
large pippete and I blow air into the tank through the top opening.
As I immerse it I already squeeze the bulb and still keep blowing air
in as I draw it out to prevent sucking the sea monkeys back up. Once
out of the take I'll draw the air in again and repeat a few times.
This seems to do the trick.