Sure the syphon can handle the full load but there will always be some bounce in the overflow... hence the second drain taking on the extra flow. If sized properly the second drain will have no problem handling the full flow if something backed up the main and will be chugging quite loud.
Well you’re ten miles ahead of my thoughts process-
Thanks, more to consider.@jaws7777
One more question- about to place my tank order.
Would you use factory overflows?
The owner of my LFS doesn’t like the overflows, says they can become traps and tough to clean.
Does anyone echo that sentiment

I’ve never had a tank with factory overflows, but I feel that they eliminate a large amount of room in the tank. I have also heard that they are hard to clean. I used the H2Overflows by Custom Aquariums and love them. They are pricey, but I think they are much better in the tank than the large factory overflow boxes. The only thing with them is that you will have to leave room behind your tank for the plumbing so you can’t have a setup sitting flush against the wall. Here’s some pictures of the overflows installed in my tank:
View attachment 1356709 View attachment 1356710 View attachment 1356711 View attachment 1356712 View attachment 1356713
One more question- about to place my tank order.
Would you use factory overflows?
The owner of my LFS doesn’t like the overflows, says they can become traps and tough to clean.
Does anyone echo that sentiment

