Does bulkhead size matter?
 

I'm new to the world of marine aquariums and I've just recently purchased a tank and have begun setting it up. I went to the pet store and asked them how to set up my bulkheads. Anyways long story short the person at the pet store gave me a 1 inch bulkhead and a 3/4 inch bulkhead. I've got the tank drilled for them so they are permanent. I was wondering which would be better to have as my outgoing flow to my sump and incoming flow from my pump.

I have a 45 gallon show tank and a 20 gallon sump located directly below the show tank as you can see in the pictures I've attached.

Thanks for any advice or help!

Attachment 6004
Attachment 6005

The one on the left is the 1 inch pipe and the one on the right is 3/4 inch

If those are the sizes of the holes in your tank I would go 1 inch for the overflow and 3/4 for the return.

Yah they are the size of holes in my tank, they are two bulkheads on the top. Is there any reason why you would do this, I would like to learn more?

It would just make it easier to match the amount of water draining from your tank and the return that way. You want them to be close to equal as possible. If you have a small drain compared to the amount of water returning to your tank your tank will eventually overflow and cause a flood. On the other hand if you have a larger drain compared to your return it would just stop as soon as it goes below your overflow line and resume once it starts filling up again, but then the noise issue comes into play here but that is easier to deal with than causing a flood on your floor. I don't know if that made sense but hopefully it did.

Yah that makes a lot of sense thank you, what is the deal with the noise? Do smaller pipes make more noise?

not really. kind of similar to your sink, bathtub or toilet, when water drains you sometimes hear a gurgling noise, which is sometimes pretty loud. same thing happens when water drains from your main tank to your sump.

large bulkhead for you drain since just gravity whereas the return is under pressure so can use the smaller.

A open drain will cause noise. Since you only have the single drain, look into the Durso, Stockman or Hofer to help quiet.

Thanks Mark that was very helpful!