Well this weekend was a bit of a pain in the arse..
I wasn't sure what my evaporation was going to be like on this tank. This weekend opened my eyes.
I topped it off Friday night before going home, with plans of coming in Saturday anyways to rearrange my office so I actually have a view of the tank.
Came in Saturday about 10am. And checked the tank, only to realize my sump had dropped by about 1.5" in water level just overnight, and that happened without any lights on. So its obviously dry in the office, needless to say I had to get a ATO sooner than later as I can't be coming into the office 7 days a week.

Although I never budgeted for a $175 Tunze ATO I figured it was time to DIY this part of the build.
Put in an order on Aquahub.com this morning..
Hopefully it gets here before next weekend, but I'm not holding my breath.