AboutTwo words: Booty Grab.
Go to the Gaia Aquarium section of the forums. It's riddled with high trigger and high payout tanks. Grabbing only takes one minute, and finding a thread takes about 5 seconds.
You can usually get 1k to 3k per tank. After about 30 tanks, you should have 30k AT MINIMUM. And that's just in 35 minutes.
Put in enough effort and you could make millions in days