Need help with building tank

[munchie]

Hello, I'm new to monsterfishkeepers. Been lurking here for a while and doing research.
I just bought a 180gal with a 40gal sump for my tank for a good price since its been sitting in my friend's garage for too long.

What I need help with is the return pump going from my sump and back into the tank. Supposely from researching i need at least 10x the tank size. But the thing is I have 11/2" pvc pipes with elbows on the back of my tank as you can see in the pictures.

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[munchie]

there are three 1 1/2" pipes. help anyone?

 

[bbortko]

The 3 1-1/2" pipes look like drains and the 2 smaller ones connected by black hosing are the returns. Is there overflows or are there jusr bulkheads on the back panel?

 

[Lepisosteus]

agree with above. the big ones are drains two smaller are returns

 

[munchie]

Just these as return and overflows. I didn't know which pump to buy so i bought the jebao dc-12000 since they're adjustable. any advice on media for sump?