Get build and money quick and long term auto clean. Start to build floors top and bottom, also start ekspandtion on the waste to energy plant. Then go to settings on your iPad iPhone and set the time forward two month. Then restart ocean tower. Activate autoclean and then go to settings and set the time back one month. Now yor floors are build and you have lots of money and auto clean for a month.
Skip the waiting for submarine passengers
Scroll down to the lower end of your tower and activate the submarine section on the left side but don't start the trip. Then scroll up to the top of your tower and start the trip. After finishing your trip scroll down again and activate the submarine section again and the submarine waiting line is full again without any waiting time. Don't forget to scroll up again before you start the trip again. You can repeat this again and again and make money very easy.