Multiple Tanks on 1 Sump? Plumbing help needed

[dragonfish1ca]

I am planning to get 4 180 gallon tanks and possibly 2 230 gallon tanks on steel racks in the next week. I would like to plumb them all together into a 120 gallon sump in another room....
Im shopping for diamond bits and bulkheads now so I figure its time to ask the experts before i go any further.
All the overflows will be atleast 12" higher than the top of the bio tower so everything will have a slope. I plan to use 1x1 1/2" bulkhead out and 1x1" return at the top on the back of each tank and use an elbow to regulate the water level. Im still trying to calculate how big my inline pump will need to be and how I will devide it into 4 returns without loosing too much head. Also the top drains/returns will be at 6' high.
-Should I PVC the whole deal seperate for each bulkhead down to the sump?
-Should I use a larger return that 1"?
-Should I make a larger pipe for all the overflows to join into and run that to my sump?
-How do I get 6 returns out of 1 fitting without loosing too much head?
Any advice or tricks or ideas will help alot and I really appreciate it
Sorry for the crude pic..... But thats about as crafty as i get with autocad LOL

 

[Liquidplants]

It looks good, I do the same with 2 - 30G tanks... I split my pump water at the pump but it doesn't mater, you'll need to have valves controlling flow into both tanks as the lower tank's water will require less "head" and more water will go to the lower tank if you don't valve the flow down. I would plumb to the tanks in PVC and then create a manifold w/ the 6 returns in tubing or whatever, each having its own 1/4turn ball valve to create the flow where u want it.

As far as the overflow you can join the 1.5" but i would make it 2" after the union. IIRC there is a sticky on GPH vs PVC size.

If you have the GPH and max head of your pump that'd be nice.
~LiquiD~