Upgrade help.

[Volcano1]

Currently have a 300, 96x 30 x 24, upgrading to a 420 ,96 x 36 x 28. Current tank has large corner overflows, upgrade has 2 holes drilled for 2" bulkheads in the back. These were used for the overflows, by using 2 90's for the overflows. Thinking this may not give good surface skimming. Any thoughts , suggestions.
also upgrade tank was 6 holes drilled for 1.5" bulkheads. Didn't want to do a closed loop, but was thinking of using these for a 3600 GPH return pump. Too little flow for each hole?
I have the following available for additional flow,
2 tunze wavebox
2 tunze 6100's
1 tunze 6200
1 tunze 6080
2 vortech mp40w.
Lighting up grade from 3 250 de, 2 150 de, to 4 400 se in lumenarc III reflectors.
Plan on using remaining equipment from the 300, xl midwest aquatics sulpher denitrifer, large geo duel calcium reactor, Volcano 1860 skimmer.
I also have 2 100 gallon sumps in the system, so total volume around 600 gallons.
This will be a mixed reef, with a decent fishload.
Any input on equipment, flow, lighting, etc. would be great.
Want to get it right the first time.

Thanks,

Todd

 

[Volcano1]

Ok,
Let's narrow it down to the overflow question for now.
Would 2 -2" 90's provide adequate surface skimming?
If not, suggestions to improve upon this would be great.

 

[jrpdriver]

I don't think that the two 90's would be enough surface skimming.

However you could point the 90's at each other and connect them with some 2" pipe. Cut slots in the 2" pipe and you should have great surface skimming

 

[Volcano1]

Thanks jrp.
Thought about making an internal overflow connected to the bulkheads, kinda a u shape, that would do the same thing. The pipe does sound easier though.