Drilling a redsea max 130

[H2o2]

Thanks but it sounds like he is using an overflow box

[viperfish]

Lifereef makes a good overflow box for the RSM. I had one when I owned an RSM and it worked flawlessly. They scare the crap out of a lot of people but if they are kept clean there is no reason they should fail. That way you don't have to drill any holes in your tank.