Overflow doubt

Hi all.
I went up to the glass shop to finally order my tank, and I got my self a hard question. Quite a few, actually. I'm going with a coast to coast Bean Animal overflow.
1- Should my overflow be internal or external? From my point of view, external will not make a dark place underneath it, inside the tank. But internal will be more safe? (at the glass shop, they told me they make it both ways and never had a problem...
2- How deep should the overflow be? What should the distance from the rim to the weir be?
I'm kind of debating myself with this questions?
I'm confident, that as always, I'll get my answers here.

Mine is internal in my tank, and I think that "dark area" stuff people always talk about is over-rated. I have corals right underneath mine and they grow just fine!

My overflow is also a DIY, and the dang thing didn't seal completely - haha, so good thing its internal or I'd have had a waterfall on my hands! I think the professionally built tanks tho don't have that problem, and the plumbing is much cleaner with the external overflow than the internal IMO. Plus, you can seal off the overflow area with a canopy, and not have to worry about fish jumping in if you wanted to!

Honestly - I think its going to be a coin toss for ya haha cuz heck, I can't even decide which to vote for!

Well, the poll tends to lean on the internal, but you sure have made another nice point there, that I've never thought about. A canopy...that can eliminate any small noise the overflow would make. It's a must, the silent. My wife prefers to hear the tv instead the water gurgles...can't understand that.lololol. Me too of course.
My only problem would be the certain of maintaining a fine tight seal between tank and overflow. But maybe even after a few years of saltwater, if needed, I can seal the joints? With that logic, all the tank walls would collapse after a few years right? ohhhhh, I'm lost...although leaning to the external option. You made me think with that canopy thing...thanks.

I've considered the same thing as you, internal vs external box, and come to the conclusion that the external (while it leaves some extra room in the tank) really isn't worth it unless you absolutely have to have that "clean" look.

Space wise behind the tank, your going to be about the same distance away from the wall. The plumbing on mine (I have the internal C2C with the BA system, 1 1/2" drains) is almost 7" out from the back of the tank. If going with an external box, your still going to be that same distance off the back of the tank. Plus it's going to cost some extra $$ to have them drill a piece of glass with that narrow dimension.

Going with the external box, you must also consider that you will still need to put in internal overflow in the tank that should be at least 1" from the back glass into the tank. I say minimum of 1" because your going to want to be able to get in there to clean if needed.

And then, as mentioned, there's always a possibility of a leak. While this is the same for either setup, a small leak is an easy repair, less water on the floor. On the external box, your looking at resealing the entire outside box, possibly having to remove it to so so. If water is leaking from the external box, then it has passes through the seam, not just the seal.

So, next thing was the question of how much light is blocked. Like was said above, I too also have sps growing under the internal overflow. Mine is clear glass, and extends into the tank 2 7/8", and blocks little to no light. You have to consider that your lights are not just projecting in a straight line, but rather a "cone", and the light spreads out around the tank. LED lighting might be the exception to this. But having areas in the tank that aren't as bright/high in par allows you to keep low light corals higher in the tank (Better for viewing).

Silence... This won't be an issue at all. I've had my mag12 full open running through this (when I first set it up), and it's dead silent. Testing on the "other" forums have show 1.5" drains will flow 3000+ gallons an hour, and are still silent. While this is awesome, your honestly never going to see that kind of gph on most home systems (unless of course you have an auditorium in the back of your house) I run mine at approx 3-400 gph, and all is good. The only real place you may get "some" noise will be on the overflow itself, where the water actually "falls" over the glass and hits the water in the overflow itself. I don't have a crazy wave in my tank, so the waterfall is steady and even. If you have a lot of turbulence at the surface of the water, then you will get a "rustling creek" sound, but even then it's pretty silent. You also mentioned having a canopy. That will deaden any noise even more.

Silicone and the structural worry. If the tank is being professionally built, I'm sure they are using the best silicone for the build. If your building this yourself, then your going to want to make sure to get the safest silicone with the highest tensile strength that's available to the public. Chances of the tank coming apart when professionally built are slim, but it can happen. Doing it yourself raises those chances.

As for dimensions, it depends on a few things. The size drains (plumbing) you are using, is the tank going to be rimless? You need enough room to remove the elbows from the internal box. As for height, the bottom of the elbow should be about 1/2" from bottom glass in the overflow. I can give you dimensions if needed.

So, now my question to you is what are the dimensions of your tank? Is a full C2C needed? You may be able to have in internal overflow/weir that does not need to go the full length of the tank, and then takes even less room inside. Also, depending on the size of the tank, you may be able to use 1" drains instead of 1.5".

Thank you Daimyo68.
The tank is absolutely being built by professionals, I do not trust my manual skills that much, lol.
It will have 105cm x 50cm x 45 or 50cm (still haven't decided) so a help with the overflow dimensions would be very nice. I would like to make it coast to coast, so I have the water surface more renewed, and less spots without movement...
I was also considering 1" plumbing, but I need to by the bulkheads first, to have the real diameter of the needed holes.
I really want to make this nice.
Glad to hear from someone that BA overflow is really silent...was it hard to tune the first time?

41x20x20 Inches, 70 Gallons

The hole needed for a 1" bulkhead is 1 3/4" US

Are you installing the overflow on the back glass or will this be a peninsula tank with drains at the end?

Here's a quick Sketch-Up I did for ya with bulkhead locations, and dimensions (if the dimensions of the tank are correct, I'll add the C2C to it).

Thanks for the design. I decided on making an external overflow because of the space it would take inside the tank.I'll assure with the guys at the glass shop it will be resist.
I've seen that you made the sketches with a 1 inch plumbing, and the diameter will have to be 45mm. I will see if they can make the holes like I've drawn them in the overflow box...

Something I will highly recommend is the use of a Gate Valve instead of the True Union Ball Valve on the siphon pipe.

The gate valve is much easier to "fine tune". The Ball Valve is cheaper but not worth the headache. Over time, you do get build up in the pipes, and on the "ball" itself. it's a pain in the butt to readjust it.

The gate valve solves this problem.

Can you help me understand what is a gate valve? Do you have a pic? I couldn't get a proper translation to Portuguese...sorry
And it's probably the best as I really want to set and forget.

+1 on the gate valves, I think they are even recommended in the bean animal instructions - I use them on any of my lines that require fine tuning!

Ok, now I know what are gate valves. Do they tend to be hard to open/close?
Today I went to try and find the plumbing shop, to buy the parts, and see the real diameter I need to ask them to drill. I forgot my GPS, and after 30 minutes wandering around in the industrial zone, I gave up. I was now looking on google maps, I was circling around the plumbing shop...I believe that the guy that invented GPS, was thinking in people like me...

Just a nice youtube video a came across...nothing to do with the topic, but couldn't resist...

sorry, something wrong with the link

one more try...

Dakuwaqa's Garden - Underwater footage from Fiji & Tonga - YouTube

A gate valve for our application can be turned using 2 fingers, instead of like with the ball valve and using your entire fist to turn it and hope it get's in the right position.

Easiest way to describe it is with a link:

Gate valve - Wikipedia, the free encyclopedia

I get mine from Bulk Reef Supply here in the states:
1" Spears Gate Valve Thread x Thread - English

I wish I would have went with those too. I hate my shut off valves. Maybe it's time to cut them out and put in some nice ones

External all the way! BUT, you do have to plan it right where as the internal standard overflows in the hobby are no brainers for the most part.

Finally I got a place to buy the bulkheads. I've been searching them before the start of this thread. After going trough all the pvc shops in Lisbon, I found one amazing, that has everything...
I'm so happy.
I bought everything for under 40€...much less than for 1 bulkhead in the LFS (they asked me 70€ for 1 bulkhead, now you can understand one reason for the Portuguese crisis...eheh)






And a merry christmas to everybody

70euro!! That is highway robbery!!!

Glad you found a real plumbing outfit that doesn't overcharge!!

They didn't have the Sanitary T's?

Whats sanitary T's? Those are perfectly slip on the inside and seemed fine...
And yes, 70€ is a major robbery.