Suggestions for 125 gallon sump design?

[dmsprague]

I have a post asking about a pump HERE so if the mods feel this is repetitive feel free to merge them. I am in the process of designing a new sump to provide filtration for 2 display tanks a 150 and 180 gallon. The sump is going to be a standard 125 gallon with a 72" x 18" foot print in my basement. I'm going to have the drains go to sock holders and have the skimmer in that compartment. I'm thinking of trying a scrubber if not will continue to run chaeto so more a less a fuge chamber. I'm wondering if it is realistic to have 4 chambers with one for frag grow out and a occasional fish that may need some TLC or isolation for various reason excluding QT for disease of course. I also will be running a bio pellet reactor but I can probably run that pump in the skimmer chamber the return to another chamber. I also am unsure of the size I should make the return chamber since this will be my first time using an external return pump. Normally I would just size it to fit the pump I am using. I will have an ATO but plan on using a separate tank to store the kalk. If anyone has any input or suggestion please share them. I have only been doing salt water for about 3 years so I have a lot to learn and would prefer to learn from those more knowledgeable than myself rather than from my mistakes Thanks

 

[mcgyvr]

Sounds like a decent plan..
Return chamber should be sized so that in the event that the overflow doesn't drain any water from your tank that the return pump runs dry before pumping in enough water to cause the main tank to overflow...