Plumbing Help with used tank

[adio1002]

First Reef2Reef post!

I purchased this 75g Seaclear 2 acrylic aquarium off facebook a few months ago.

From my research the tank is an AIO tank, but the previous owner drilled it. Theres 3 holes, one on the side (Return?), one on the back directly above, the one on the bottom. The tank also came with an overflow box.

Could someone guide me with the plumbing of this tank? I've watched videos, read posts, but can't seem to figure out what type of drilled setup this is.

 

[Cichlid Dad]

Study how sump plumbing works and design your own . Balk Reef Supply has all of the bulk heads with dimensions both for tank hole size and PVC sizes. It will also tell you what size seals to use for the bulk heads. You can also plug any or all of the holes. With three holes depending on the hole size, I would run 1 return, 1 regular drain and 1 emergency drain. Return on the side, regular drain from the back of the tank ( use a 90 on the inside so you can control the water level depending on how long the PVC pipe goes up) and the emergency coming from the bottom of the tank.

 

[Cichlid Dad]

Ps ditch what ever plumbing came with the tank. I don't see anything that looks like it would work on that setup.