[Ram04]

Hello everyone, I am new to the site but not the hobby. I just bought a new 150G acrylic w/ built in overflow. It has 2 drain holes. Can i use 2 standpipes in 1 overflow? I have never had an aquarium w/ built in overflow so i have no idea if it will work.

Thanks,
Jerry

[Ninong]

Hi Ram04, welcome to Reefland!

What brand of acrylic tank do you have? Is there only one built-in overflow? Where is it located, center back wall??? What size are the two holes? Do they have bulkhead fittings mounted in them right now or are they just holes? Are they both the same size? And both of these holes are drilled in the bottom of the tank, right?

[Ram04]

Thanks Ninong!

The tank is made by Acrylic Creations Inc. The holes are the same size 1.5".
There is only one overflow in the middle back and the holes are drilled in the bottom of the tank. And the tank is 30" tall. And i have the bulkheads but they are not mounted.

[Ninong]

Originally Posted by Ram04

The tank is made by Acrylic Creations Inc. The holes are the same size 1.5".

Hmmm... Here is a chart with hole sizes (A) for standard size bulkheads: http://www.plumbingsupply.com/bulkhead.html

As you can see from the chart, a 3/4" bulkhead requires a 1.625" hole and a 1" bulkhead requires a 1.875" hole, etc. So I'm not sure what size bulkheads you will be able to use if the holes are 1.5".

The reason I asked that question is because some manufacturers drill two holes, one for the drain and one for a through-the-bottom plumbed return line that then exits through the side of the overflow compartment into the tank. My 120-gal Starphire glass tank, for example, has a single corner overflow compartment with a 1.5" drain bulkhead and a 1" return bulkhead. Obviously the hole for the 1.5" drain was 2.5625" and the hole for the 1" return was 1.875" in diameter.

However, some manufacturers provide two drain holes in the same compartment, which is probably what your tank's manufacturer intended. Perhaps you should double check the dimensions to make sure they are both really 1.5" and not 1.625". However, even a 1.625" diameter hole (3/4" bulkhead) sounds too small to me. I would think that for a tank of that size they would use at least 1" drains???

[Ram04]

I went and remeasured. There are a total of 4 holes, 2 for drain, and 2 for the return. The drain holes are 1 3/4" and the returns are 1 3/16"

JD

[Ninong]

Originally Posted by Ram04

I went and remeasured. There are a total of 4 holes, 2 for drain, and 2 for the return. The drain holes are 1 3/4" and the returns are 1 3/16"

JD

The larger holes are for the drains and the smaller holes are for the returns but you had better call the manufacturer to find out exactly what size and what brand of bulkheads they are for.

[Ram04]

I will call them and find out. The bulkheads that i have are the ones that were supplied with the tank. Not sure if that is any help. Meaning i didn't just go buy them to 'kinda' fit the holes. But i am not sure if it is posible to use 2 standpipes in the same overflow.

JD