plumbing advice please!

[danskim]

I will be drilling my 30g oceanic cube soon, but I had some questions about what pipe diameter would be best.

I'm aiming for about 1000gph total in the tank, which will hold mainly LPS corals.

I plan to have a 1" drain from my overflow into a sump which will then be returned by a pump (yet to be determined) which will have 2 returns into the tank.

I also plan to have a closed loop with 1 drain and 2 returns as well.

I will be using either 1/2" or 3/4" ID locline. I am looking for advice as to whether I should do one of two things:

1. Use 1/2" bulkheads for the 4 returns feeding from 3/4" pipe that splits into 2 via a reducing PVC Tee (3/4" inlet, two 1/2" outlets). Then I would use 1/2" locline Y and have flared nozzles on each.
2. Use 3/4" bulkheads for the 4 returns feeding from 3/4" pipe with a regular 3/4" PVC tee. I would then use a locline Y that is 3/4" to 1/2" reducer with flares.

What do you guys think?

 

[Holyreefer]

The calculator say :
Recommended minimum drain pipe diameter = 1.31 inches
Recommended minimum linear overflow size = 15 inches

Its under calculator conversions on the home page

 

[danskim]

yeah but i think that's taking into account just one intake.
i am planning on two intakes - 1 for the sump and 1 for the closed loop.

edit: oh yeah, i will probably do probably around 300gph through the sump and 500-600gph for the closed loop.