Pre-Drilled tank and Herbie Overflow

[Grey Legion]

Howdy Folks,

Proud owner of a 48x24x16 predrilled tank.

The tank is drilled twice in the bottom and was made for (1) overflow"durso" and (1) return.

I want to switch to a herbie style, so my question is this.

The two holes are different sizes lets say Hole A is 1" and Hole B is 1 1/4"
I'm not sure of the sizes but you get the picture.

What hole should I use for overflow and what hole should I use as emergency drain ??

Thanks!

 

[thegrun]

It would help a lot to know the actual sizes. Normally you would want to use the smaller hole as the primary drain and the larger as the emergency, but the small hole may not be large enough to handle your intended flow.

 

[CafeReef]

You would be better to have the smaller hole drilled to the same size as the larger. This way the emergency and main siphon are the same size.

If there is space with them, drill a third for the return. With mine i have my drains in the base and return drilled in the back.

 

[monkeyruler90]

awesome tank, glass or acrylic?

 

[Grey Legion]

Thanks for the replies.

Tank is Glass and is brand new so I won't be drilling it as I want the warranty as it is covered through my LFS.

I'll be sure to measure the bulkheads and get the sizes.

My plan is to use a hang on return and use the smaller hole as the herbie and the large hole as the emgency. For flow I'm sure I can get what I need or at least work with what I got.

If all else fails I can always go with the supplied durso..

Any other thoughts?

 

[JMorris271]

usually the 1 inch is used for emergency and the 3/4 inch is used for full siphon. You can reverse it if you want the risk of an overflow.

 

[CStrickland]

usually the 1 inch is used for emergency and the 3/4 inch is used for full siphon. You can reverse it if you want the risk of an overflow.

This.

Also, you aren't married to the hole sizes. It's about the pipe width, within reason. So you want to measure the bulkheads themselves. Like, if you do wind up with a 1" and a 1.25" I think you can safely reduce them under the tank. On my herbie I have a very wide, adjustable standpipe and e drain inside the overflow, it's only 1" and 3/4" under the tank. I bet your tank is like mine, and a 1" drain and 3/4" emergency will pop right on there.

Congrats on the new tank!

 

[Capiross1]

Thanks for the replies.

Tank is Glass and is brand new so I won't be drilling it as I want the warranty as it is covered through my LFS.

I'll be sure to measure the bulkheads and get the sizes.

My plan is to use a hang on return and use the smaller hole as the herbie and the large hole as the emgency. For flow I'm sure I can get what I need or at least work with what I got.

If all else fails I can always go with the supplied durso..

Any other thoughts?

If the smallest of the 2 holes is at least 1 inch you'll be fine using that as your main and I definitely would not try to redrill the holes larger especially on a brand new tank, and I'd get a good gate valve marine depot has the best price I've found good luck!