I realize that this is an old thread discussion I stumbled upon, but for this poster and anyone interested, Dawn is perfectly safe in the pool, and, it does not actually KILL the bugs, it prevents them from being able to swim, which in turn makes getting to oxygen impossible. Dawn, or any other detergent, does not block, nor prevent oxygen from anything. Starving something from oxygen would require removing the oxygen, in which case it wouldn't be water any linger. Just hydrogen.