Is Durso unsafe with valve on drain?

[rknott]

I am setting up a 75 gal tank with a 30 gal sump. New to a systems with a sump. It has what I have learned is called a Durso set up. After my initial test run and hearing the massive noise I did a bunch of research and pretty much resigned myself to converting to a Herbie. After a stop at my LFS they person there told me to add a 90 and a gate valve on the drain of my durso. That would quiet it down. I asked what happens if the valve is shut to much, wouldn't that flood my house. He said that shouldn't be a problem if you get it set up correctly. It is pretty easy for me to envision something getting stuck in the drain and causing a system overflow. About the only insurance of an overflow I suppose would be the sump running out of water. in the pump section. Is that the common fail safe? Would I be safer going to a herbie with the emergency overflow?

I have it successfully running outside at this point (after spending forever making sure water wasn't slowly rising and overflowing, or falling and going back to massive noise).

Pics attached for reference. NOTE, in the pic you will see a ball valve not a gate because my local hardware store didn't have a plastic gate so I am going with this as a test.

 

[Lukas75]

You are correct, without a second drain there is no way I would restrict the flow on the main drain pipe.