Don't forget that you can add a relay board (to control things) and also an ethernet/wireless shield if you want to control things via a web interface.
Besides the DS1307 RTC, you can also consider using the DS3231 chip; it does not cost significantly more than the DS1307.
Something like this (though this is an old photo; I've cleaned up the wiring, added a few components and switched to the TFT LCD Touchscreen)
as I was working I was thinking about this, on how people would plug in a probe etc to monitor/control their PH, co2, salinity, temp etc.
my other concern was how small the screen is I was hoping to have a screen at least 6x6 inches so it could be easily seen from a distance. Maybe something we could look into?
Dark PM me to please I have an idea I want to run by you that is kinda off topic.