okay i am ready for the new tank. glass cages has a 180 thats 72 x 24 x 25 Tall for $550. i am not going to have them drill anything but drill it according to my picture. tell me what you guys think.
1. the red dots are going to the sump and will be 1" the blue is the return from the sump and they are both 1" and will be pointed downward at about 60 degrees
2. the light blue dots are going to two mag 12 that will alternated every 10 minutes and will have a 1" drain out with 1" returns that come back to the brown dots that will have two arms that sprout off
3. the pink dot will be attached to a mag 12 that will always be on and be come out through the green bar at the top with the lines pointing down
1) Using one inch 90 degree fittings and turning them down ward will mean you will not be skimming the nutrient rich top layer of the water, plus only skimming an average of 700 gph combined. The 1" size is pretty overflow is pretty minimal even with both in use. 1 1/2" bulkheads for the overflows would actually allow more than twice the maximum flow which means running them at half capacity would make them very quite and would give that redundancy that is always nice with overflow. It is amazing how they manage to find ways to get clogged. I would recommend overflow boxes even if they are just home made glass boxes , therefore without slots. They are simple and cheap to build and will skim all water from the very top of the tank.
2) I would recommend larger pumps and feed bulkheads for your closed loops. A tank as large as yours could easily handle Sequence Snappers running 2500 gph instead of the Magdrives. The wattage used would be virtually the same with twice the water being pumped. The intakes would need to be 2" and the returns could be four one inch bulkheads reduced to two 3/4" nozzles or T'd to feed four 1/2 inch nozzles
per pump. Or at least put in larger feed bulkheads in anticipation of larger pumps. Mag Drive pumps are pretty poor pumps, whether used inside or outside a sump. I would consider PanWorld, which are as good as Iwaki's (which are considered top of the line). Or if you upgrade the flow I would recommend Sequence Snappers.
3) Once again I do not recommend Magdrive pumps. I would use a PanWorld 50PX-X rated at 1110 gph with power consumption of 90 watts. They are cheap, quiet and run cool. They were designed by the same engineer who designed the Iwaki pumps. I always recommended oversized bulkheads to allow for less friction and ease in upgrades. Installed with threaded portion on the inside on returns allows for the installation of Loc-line swivel nozzles on 3/4inch male threaded adapters that can be used with 1 inch to 3/4 inch bushing reducers screwed into the bulkheads. Or if you like lots of small nozzles, run two 1" bulkheads reduced down with bushings to 3/4" and use Loc-line 3/4" Y's that have two 1/2" nozzles on each Y. All swivel for adjustability.
Lots of flexibility, lots of flow or potential to upgrade to lots of flow. Check out the glass-holes site for pictures of slotted inlet boxes they make for me for closed loop inlets.
http://www.glass-holes.com look under custom work Dave's end of semester extravaganza.