Holes in Tank

[trillionaire]

I just bought a 220 gal arcrylic tank. There are five holes in the bottom. Two of them are in the over flow box and I know what those are for (drain and water return). The other three are in the tank. The are in a straight line about a foot apart, the two in the middle are one inch holes that are threaded on the bottom (PVC going through them). The one on the far right is 1.5 inch hole with PVC, not threaded. I bought this tank used and I didn't realize the holes were there until I got in home. The diminsions of the tank are 72"W x 41"H x 22" D. Any idea what these holes are for. This is my first saltwater tank.

 

[lcc]

the holes in the bottom of the tank in a row might be for air lines. I have seen this type of set up at the local fish store.

 

[mr . salty]

The threaded holes are for the return lines from your sump.You will need to get some threaded barbs to attach the hoses to.The third hole could be either another return,or if you put a pipe in it on the inside of the tank going all the way up above the water line you can use it to run power cords into the tank without seeing them hanging over the side of the tank.