I have recently purchased a 125 gallon tank. The tank came with pre drilled holes in both back corners each side has 2 holes. I am wanting to run a herbie overflow on this tank as I have read it is a great overflow system. So in order to run this system, I need at least 3 holes per corner 1 for full siphon, emergency drain, and return. I have been throwing a couple ideas around and would like input from more experienced people in the hobby.
Option 1: Drill another hole in each corner resulting in 2 total full siphons, 2 emergency drains, and 2 returns. If I have enough room in the corners to drill another hole as I have not measured anything just by looking at it, it looks like it might be a little tight to fit another hole/pipe in.
Option 2: Don't drill the additional holes and run 2 full siphons one in each corner, 1 emergency drain, and 1 return.
Option 3: Don't drill the additional holes and run 1 full siphon, 1 emergency drain, and 2 returns.
Options 4: Don't drill the additional holes and run 1 full siphon, 2 emergency drains, and 1 return.
These are the ideas I have bouncing around in my head. Thanks for any input and I appreciate it.