Overflows on large tanks...??

[rovster]

I feel like I'm pretty knowledgeable with nano and "regular" sized tanks, but I'm starting to research what goes into owning and operating a big boy tank. Well for some of you this is small, but something in the 250-350 range (DT). You see all these large stock tanks with multiple overflows and I always wondered if that was really necessary. I am an SPS nut so I always have tons of auxiliary flow in all my tanks, and I thought you just need enough flow to process the water in the sump.

Ideally I love the idea of a large external overflow, but realistically if I ever upgrade that wont be possible because I don't have access to a fish room or garage so I won't be able to reach the back of the tank if anything needs a fixin'. I thought about an external overflow on one side but then that side will not be viewable, not cool, LOL! A "ghost" overflow does not help either because of the access issue, although the idea of it sounds appealing to me.

So that leaves me with either a C2C internal which I don't like the look of, and still has access issues, or a traditional overflow box.

So, that brings me to my questions....how do you determine how large these boxes need to be, and how many you need? I'd prefer a single box, but willing to hear what the experts have to say. I'd definitley set it up with 2-3 drains (bean/Herbie).

Thanks for any input. I'm trying to warm up the wifey to let me pull the trigger, but realistically it may be a year or 2 before permission is granted, but that doesn't mean I can't start the wheels turning.....:celeb1:

 

[dave.m]

Usually you would try for 5-6x tank volume turnover per hour to the sump. The remaining flow would be achieved in the tank with either powerheads or a closed loop. That's what determines the size of the overflow pipes. The number of pipes is determined by the drain system style you opt for (Durso, Herbie, Bean Animal, etc.).

Dave.M

 

[mfarris]

I have been planning a large tank (475 ga) also and have been debating on what type of overflow to use. custom aquariums is building the tank but they only want to sell me their overflows. my tank will be an in-wall build but will be viewed from 3 sides (foyer, dining area and office/ fish room) I really like the idea of an external overflow but realize I will need an internal box also to make it work since the glass won't have a simple wier at the top. I am sure some folks have this setup but would like to see some pics/ instructions on how to build it.

 

[dave.m]

Look up the ghost overflow. It might be what you're looking for.

Dave.M

 

[Ricardo18]

Look up the ghost overflow. It might be what you're looking for.

Dave.M

AGREED..it is the way to go if you need a small internal box

 

[mfarris]

thanks!

 

[rovster]

Usually you would try for 5-6x tank volume turnover per hour to the sump. The remaining flow would be achieved in the tank with either powerheads or a closed loop. That's what determines the size of the overflow pipes. The number of pipes is determined by the drain system style you opt for (Durso, Herbie, Bean Animal, etc.).

Dave.M

OK, tank will be 300gal +/- 20 gallons plus another 80-100 in sump so lets round it to 400 gallons. So I'm looking at an overflow that will handle 2400gph? The more I think about it, I think a ghost style or external may be best, and I'll just pray that I don't have to ever change a bulkhead. It will definitely be herbie but at that size I don't mind a bean. I currently run a herbie on my 100gal and my return is wide open but it also feeds a manifold.

What sized piping should I be looking at? How long does the weir need to be? Thanks!

 

[dave.m]

There are lots of calculators on-line, including here on RC (see main page under Calculators)to determine these things. Also, if you're going for the ghost overflow, you can contact them directly for assistance. You should finalize your tank measurements first to ensure correct calculations.

Dave.M

 

[Vinny Kreyling]

I think for 2400 GPH you would be better served with a Bean drain.
I have not been able to ACTUALLY determine why but my Herbie drifts and I have to play with the drains.
One theory is my DC pump feeds more than just returns.

 

[urbaneks]

An external overflow doesn't have to be huge. They are especially easy to hide if you do a peninsula style aquarium. On my tank pictured below, the over flow is concealed behind the black wood pieces that butt up to the wall. I can remove the wood pieces to access the bulk heads, valves etc. The 2nd pic shows the access when I remove the wood pieces. Perhaps this is an option for you.


.

 

[rovster]

Thanks Brad, but peninsula is not an option. I would have done something similar to you with a concealing panel I guess the other option is to make sure the bulkheads and overflow is offset to one side so I can access it. I'm looking at 7ft against the wall. Anyone done this? Is this something I'm making too big an issue of?

And thanks Dave for the link. I'll look into it. I was going to contact Synergy about their larger overflow but at 2500 gallon capability that does not leave me much margin for error....