Opinions on plumbing needed

[Galail52]

I am preparing to plumb my new tank but am unsure how to utilize the pre drilled holes. The tank has 4 holes drilled in the overflow box, 2x 1” & 2x 3/4”. I would like to de a bean animal, but should I use. 3/4” as the main drain and the 1” as emergency? Or should I use a 1” as main and a 1” and 3/4” as emergency?

please let me know what you would do.

 

[Quietman]

Use the 1" as the emergency- no valve (bigger is better), Use one 3/4" as the primary drain (full siphon with control gate valve) and the other 1" or 3/4" as the secondary drain (partial flow - valve not required). With the remaining 1" or 3/4" I would use as return.