Do I need to turn the unit off and take it out of the pool at the end of the day?

No, just leave it floating in the pool. No need to switch OFF either. If the flashing LEDs bother you when Betta keeps working into the night, you can switch the power OFF by pushing on the red power button and leaving Betta floating in the pool. Turn the power back ON the next day after sunrise when you want Betta to go back to work.