Noob Plumbing Help

[Miller Aquatic]

I’ve had quite a few saltwater tanks but never one with a sump. So I got a 135 gallon tank which has 2 holes I was thinking one return and one overflow. Each hole is 2” and the overflow box I have is 800gph Fiji box(I think).The overflow box has two 1.5” inch bulkheads herbie style drains. These two holes are on the side of the tank and was wondering the best way getting water to and from the sump with the least head pressure?
I’m gonna convert my 60g breeder into a sump soon. (Fowlr system) also I’m in the middle of scraping off old paint.
Would this setup work?

 

[Miller Aquatic]

so I’m assuming when I start plumbing the return should be 1.5” pvc and the overflow should be two 1” pvc? Also will the 800 gph return pump be ok? I’m planning on having large power heads for in tank flow.

 

[MarineandReef Jaron]

The two holes are likely both for an overflow box. The larger boxes use 2 1.5in bulkheads. Link to the larger overflow box below. For the return, I would recommend going over the back or drilling a new hole if one is not already drilled.

Fiji Cube 1200 GPH External Overflow Box

The Fiji Cube 1200 GPH External Overflow Box works with rimless, eurobrace, and standard trim aquarium tanks.

www.marineandreef.com

 

[Miller Aquatic]

I thought that 5x turnover overflow would be sufficient through the sump

 

[Miller Aquatic]

Also looking at the larger overflows it looks way too close for those for hole sizes.

 

[MarineandReef Jaron]

Since this is a used tank I do not know for sure what the original owner did. However, Nobody who knew what they were doing would use a 1.5in bulkhead as a return. It is possible this was a double drain setup without an overflow box.