I've read that algae have photosynthesis cycles that cannot just turn on/off easily and therefore require consistent light to grow. If you put your lights on a timer, one that has two on/off settings, then it will automatically turn lights on for say 3 hours, then off for 2 hours, then on 3, and finally off for the night. I have one that cost me $10, not digital, just place little arrows when I want the light on/off...easy. If you go with live plants, this won't impact them. Regular plants have a more sophisticated process that can photosynthesize immediately the light is on.
Also, just wanted to add another comment about the heater. In the winter, even in South Texas, does it get below 75 at night? If there's more than 4 degree difference between day and night, I would think a heater would still be necessary. A submersible is not highly visible and it self-regulates so you don't have to turn it on or off. Just set the thermostat to the temp you desire and it will turn itself on/off to keep the temp regular.