Based on the advice in this thread I think I am going to select the MRC MR-2R Skimmer as it looks to meet the tank requirements and is small enough to fit in the sump. Also I removed the gate valves on the return pumps and also the check valves as well. Will save around $100 and as others have pointed out if the tank is properly plumbed they will prove unnecessary. I do not think I am going to try to manifold the return pumps as I would rather drive other reactors, etc off individual pumps in the sump to try to retain as high a tank turnover as the overflow and returns will allow. Happy to be corrected or hear other view on that.
Ok so now I am going to be controversial.
My rule of thumb. Is better to have and not need than to need and not have.
Check valves yes are a flip of the coin. If your returns are so deep in the tank they will siphon enough to water out to overflow the sump well thats the only consideration to have them. What is plumbed right? You wont know until test time.
As far as the gate valves on every line. Well yes you can be selective.
But this is where I am a fan of having them. Never know what adjustments may be needed. You maybwant to ballance the drain lines to control noise.
You may have to only use one drain line and have to slow it down but wont be able to if its not there. I know this is doubtfull but on occasion it does.
What if the in tank overflow box leaks or cracks at the bottom. Be nice to shut the drains off.
Yes its an expense and all but its also a failsafe.
On my next build I intend on having a ball valve followed with a gate valve.
The gate valves are best for tuning, the ball valves are best for a 1/4 turn and its closed off in a second. Less water on the floor.
