Overflow and Sump setup question

[RevK]

I am currently upgrading from a BioCube 32 and purchased a used 48x24x24 120g with two internal overflows each with two drilled holes in each overflow. Currently it is setup with a Durso drain in each to hard plumbing into the sump (1" PVC) and a 3/4" return line. It is currently setup in the garage with just freshwater and I am hearing a lot of noise coming from the drains into the sump. It does seem to come more from the exit into the sump than the drains in the tank itself. I am also a little concerned there is no "backup/emergency" drain.

1. Should I be worried about the lack of a emergency drain (there are two separate drains one in each overflow)
2. Any ideas for how to make it run quieter? (I through about putting a spears gate valve on the drains, but read several places that putting a valve on a single drain is a BAD idea)

Thanks for any suggestions!

 

[chaples55]

I would probably ditch the dursos and run a Herbie setup on one side and run both return lines on the other side. Either that or try to run a full siphon on one side (with a short drain pipe significantly below the level of the overflow grille) and make the drain pipe on the other side ever so slightly taller than the lowest point on the overflow grille such that it gets just a trickle in normal operation but can still act as an emergency drain if needed. This would essentially act like a Herbie as well, just a little trickier to setup since the short and tall drain pipes would be behind separate overflows.

 

[scuba steve]

You can add a gate valve to one of the drain pipes. You do have 2 drains, even if there are in their own separate overflows.

 

[AWarnick]

If The herbie in different chambers doesn’t work out you could convert the return pipes into drains that act as
full siphon and the 1” pipe as emergency. Either way you are going to need some gate valves