I just got a bigger tank, and its drilled in the back. Now what??

[wings4wheels]

I am moving, and instead of tearing down and reassembling my 90 gallon reef, I am going to set up a 125 gallon, using as much from the 90 as I can, to make the transition easier (and appease my desire for a larger tank). I found a used tank, and it has three holes (with bulkheads) along the back side of the tank toward the top of the glass. I am wondering what I should do with these, and how to plumb them for a sump. In my mind I see a gravity feed to a sump, a return line, and a 3rd "mystery hole." Help me out please!

Thanks in advance

 

[veselym]

In a 125 you should have 4 holes...2 for draining (one acts as a back up) and 2 holes for the return

 

[wings4wheels]

Well, this one has three, and I DO NOT plan on adding a 4th. so, I would assume that I would have two for draining and ONE for return??

 

[veselym]

I would do 1 for an intake and 2 for return...you can do it how you want really but most do 4 holes regardless of tank size

 

[SeeingGreen]

Put a picture?

 

[wings4wheels]

pictures to come

 

[wings4wheels]

Here is an early pic.

 

[wings4wheels]

Ready to move everything over.

 

[ps2cho]

Thats a tough one. You really don't want just one overflow. If it gets blocked you flood. I would really encourage you to drill a backup hole next to it, then silicone an overflow box from ebay.

 

[TitansFan]

I would do those as overflows and do over the top returns.

But I would silicone in over flow boxes.

 

[wings4wheels]

Why couldn't I use two for overflows and one return?

 

[TitansFan]

you could but consider overflow boxes otherwise you will have gaping holes to suck fish in and battle the tank water level

http://www.bulkreefsupply.com/cpr-retrofit-overflow-box.html?gclid=CMeDooOptcACFScV7AodPS8A0g

 

[scason]

Looking at those, looks like about 10 in materials to build. The biggest part with drilling is finding out if the glass is tempered or not. Well considering that they holes are already there, well thats the hard part. It would be really easy to drill the final hole and have a symmetrical design and make it easier for a return flow pattern. always better to do it now than wish you had after the tank is established.