Oh no, not another overflow question! :)

[ErinD]

I know, I know - there's a ton of these on this (and other) forums - but this one is slightly different and comes from a slightly different place of intention.

I'll start with the foundation -
45 gallon mixed reef
HOB Octo protein skimmer
Canister filter for mechanical filtration
mixed live and dead rock

My refugium build is small - 5.5 gallons - really just looking for a place for chaeto, pod nursery and to get my feet wet in refugiums.

I won't be drilling this tank, so a HOB overflow with siphon is my toast and jam for this build.

Here's my question:

Because I won't be incorporating anything more than a filter sock for filtration in this sump, do I need anything more than a nano hang on back overflow with a max flow rate of 200 gph? This isn't so much a question based on price, but on utility. Would something larger even be beneficial for any other reason than if I wanted to utilize it for a full filter system (or protein skimmer incorporation) in the future?

 

[W1ngz]

I'd consider a bigger overflow, not for the flow, but because bigger overflows have at least 2 drains. One single drain in a nano hang on would keep me up at night.

The flip side to that though, since your refugium is so small, there's not a ton of extra water that will be pumped over the rim of the display if the siphon quits or the drain gets blocked.

 

[ErinD]

I'd consider a bigger overflow, not for the flow, but because bigger overflows have at least 2 drains. One single drain in a nano hang on would keep me up at night.

The flip side to that though, since your refugium is so small, there's not a ton of extra water that will be pumped over the rim of the display if the siphon quits or the drain gets blocked.

I'm less concerned about the 1 outlet than I am the flow of water going into that small of a sump. BUT, I'm more concerned about a nice, efficient, well tuned in and out than I am the cost. The nano has a 3/4" outport whereas the next step up is a 1" - the pump I'm planning to use is a 1/2", so I was drawn to the nano for that reason as well. As norm, I'm coming back up with 5' of head so I just wasn't sure that a bigger flow would do anything more than complicate in such a small stop over as 5 gallons.