What is an eco-friendly way to maintain my air conditioner?

Our air conditioner constantly drips water outside the house, which has caused a small eco-system to form in the puddle. Tiny little frogs live there which chirp all night long. We love it!

But our AC repair guy says we must pour a cup of bleach in the AC drain every few months to prevent scum build-up. If I do pour bleach down that hole, it will drain right outside the house into our new froggy paradise.

One idea I have is to go ahead and pour the bleach down there, but then pour a lot of water after it, and collect it all before it has a chance to kill our frogs, but how much water do I need to use to make it safe again, and how do I know when it’s running clean?

Is there a non-toxic alternative to the bleach?

It’s a combination furnace and AC unit by Goodman Manufacturing Company. Model # ARUF42C14AD I’m not sure if you need more information.