Drain plumbing will this work?

[Chris Spaulding]

I am getting ready to plumb a new to me tank. It has dual overflows with a one inch drain in each overflow. Can I combine the two drains in one pipe below the stand into a 1.5 pipe so I only have one pipe going into the sump?
1 inch pipe flow rate gravity fead is 960 gph
1.5 pipe flow rate gravity fead is 2100 gpa.
Attached is a crude drawing showing what I am thinking.
Reason I am thinking this was is I am wanting to use a filter roller and the input pipe on this one is 1.5 .

 

[lapin]

Should work but you might want to have a gate valve on each drain to balance them out.