With the 100g since it comes with the 57g sump, cabinet space is limited. Outside the cabinet on the right side of my tank I will have the ATO res and a QT tank. I don't place on housing a ton of items outside of the cabinet but a few items for sure. I will likely have my controller items etc. mounted externally but that will be determined once the tank arrives. I want to measure it all out best I can. I am also considering attaching a UV sterlizer to the right 3/4" return pipe just before it enters the tank. I think everything else I can organize nicely inside without being crammed.