Weir Overflow Location

[Soren]

A question has been rolling through my mind while planning my 90-gallon reef tank:
What location should I choose for the overflow weir drain standpipe and return pipes?
I have a typical 90-gallon aquarium (48" long by 18" wide by 25" tall) that does not have any holes drilled for overflow. Since I plan on a sump system, I would like to add an overflow.

I know this ultimately is a matter of personal opinion, but I am interested in what you have to say about this.

Do you prefer a central weir with standpipe and returns in the middle?
Do you prefer a corner weir with standpipe and returns in the same corner?
Do you prefer a weir with standpipe in one corner and the return in a different corner?

What are pros and cons to each arrangement?

Right now, I plan to have the display tank (DT) overflow drain to the side of the DT into a 40-gallon sump-refugium with deep sand bed for growing mangroves which overflows into a 75-gallon sump located under the DT. I am leaning towards having the weir with drain standpipe on the back corner on the same side of the DT as the mangrove sump with the return coming up on the opposite back corner from the main sump. This allows for flow across the display tank to allow for more thorough flow management. This would also leave more central space open for free-swimming fishes. Is there anything you would advise that I am missing in considerations?

Also, can you recommend bulkheads and common pipe sizes for standpipe? How do I calculate standpipe diameter? I plan to have two return pumps each capable of about 1500 gph flow to create the main flow in the DT.

This approximating model of the current layout includes a central weir, but I do not like how much space it cuts out in the middle.

Thanks,
Soren

 

[CMMorgan]

Dude, Your in my headspace! I have agonized over this for weeks. I'm escaping the typical 90... so over those dimensions. Let me mess with your thoughts for a minute...
One of my biggest complaints about m 90 is the overflow. Mine has a single overflow, off center to the left. It uses a Durso and a return directed towards the right side with loc line... there is room on the left side for a wave maker.
I have noticed that the water really doesn't flow nicely. It's just off balanced.
Have you considered keeping the overflow in the middle but drilling the back instead of the bottom for a ghost overflow? Then run dual returns on both sides of the overflow. That will give you fabulous filtration and surface skimming. Bonus, you don't have to get down under the stand to plumb from below. Less chance of flooding, too.
Don't you just love it whwn you ask for someone to pick A, B or C and they opt for D?
Love the idea of the secondary refugium. I've seen a few dedicated fuge and they can be stunning in themselves. Also a good time out if you have a fish that misbehaves.

 

[Water Dog]

Central internal skim box location with dual returns flanking the overflow...

 

[CMMorgan]

Central internal skim box location with dual returns flanking the overflow...

Exactly what I was thinking....

 

[Soren]

Dude, Your in my headspace! I have agonized over this for weeks. I'm escaping the typical 90... so over those dimensions. Let me mess with your thoughts for a minute...
One of my biggest complaints about m 90 is the overflow. Mine has a single overflow, off center to the left. It uses a Durso and a return directed towards the right side with loc line... there is room on the left side for a wave maker.
I have noticed that the water really doesn't flow nicely. It's just off balanced.
Have you considered keeping the overflow in the middle but drilling the back instead of the bottom for a ghost overflow? Then run dual returns on both sides of the overflow. That will give you fabulous filtration and surface skimming. Bonus, you don't have to get down under the stand to plumb from below. Less chance of flooding, too.
Don't you just love it whwn you ask for someone to pick A, B or C and they opt for D?
Love the idea of the secondary refugium. I've seen a few dedicated fuge and they can be stunning in themselves. Also a good time out if you have a fish that misbehaves.

Thanks for your input, CMMorgan.
Don't make my decision on tank size harder! I already have the 90-gallon tank and don't want to consider additional tank expense right now!
Though the poll has only three options, I am open to more considerations. I have been considering drilling the back instead of the bottom for a few reasons: minimal flooding in case of plumbing failure (since holes will be located near the top) and possibility of the bottom glass being tempered and not able to be drilled.
The other huge advantage of drilling the back is that the overflow box is much smaller than a full tower weir, leaving more open swimming space. Is there a reason that a large tower weir is preferable to leaving an exposed standpipe for bottom-plumbed tanks?
The downside to drilling the back is that the tank needs to be farther from the wall and the stand needs more space to allow for the plumbing behind the tank.
Another consideration I did not include in the poll is to drill through the end of the tank similar to a peninsula aquarium. I do not have room to use it like a peninsula (it will be in the corner of the room), but it might be better for me to use more space end-to-end than front-to-back due to the layout of my living room.

Central internal skim box location with dual returns flanking the overflow...

Thanks for the picture reference, Water Dog. This is one of my considerations, though my return might be done slightly differently to allow flow through the specific plan I have in mind for live rock layout.

 

[CMMorgan]

Sorry to add to the choices... but I think we are on the same page. I was very against pulling away from the wall at first. Then I realized how much easier it would be to plumb and SOLD! I have a woodshop, so we decided to make the stand deeper and run a matching filler board to close the gap in the back. I'll secure it with dowels on the bottom and a mag catch against the wall to keep it straight. I'll be able to easily remove it if I need to check pipes and I can reach the back to magnetize a wave maker, etc. If I build a hood, it will all blend.
I also considered the end overflow but my thought was the circulation and skimming would be inefficient.
If for no other reason to drill the back.... you nailed it - no flood.
Can't wait to see the outcome!!! Happy Reefing!!!

 

[X-37B]

I go corner.
Try cleaning or removing something from the center overflow.
I will go peninsula next time. That equal one more side for corals, lol.
Peninsula with the overflow box on the outside like above would be awesome.