Tank Journal Archive

192k

Member
Nov 17, 2011
915
336
Northside Brisbane, 4017
Initial Tank Planning & Design
I have always really liked the idea of external overflows in aquariums. When partnered with black acrylic, they offer the clean and simple look I am after.

External Overflow Advantages:
(1) Take up no space inside the tank
(2) Looks cleaner inside the tank, no boxes or pipes visible.

External Overflow Disadvantages:
(1) Manufacturing costs are higher. More glass is required and acrylic.
(2) Need additional space behind or next to tank. Tank is unable to sit close to rear or side walls.

The bulkheads I am using are 32mm Slip/Slip and they require a 51mm hole. The hole spacings I have come up with are below. One diameter hole width apart from the front, sides and back of the glass panel. Would these hole spacings be adequate?
image.jpeg


I came up with the idea of having a lower drain section, so I wasn't limited by the external overflow's height governing the standpipe's height.

Design # 1
The first design incorporates a full length Coast 2 Coast External Overflow with lowered drain section. View is from behind
image.jpeg


Design # 2
The second design is an full width, end overflow with lowered drain section.
View is from the side
image.jpeg


So with the two options, I am leaning towards option # 1 as in theory, it should provide more surface skimming.

Any thoughts, suggestions, ideas? ;)
 

n0rk

Member
Aug 10, 2011
412
250
Brisbane
It's a tricky thing. The full width is good in that you get a wider area for collection of detritus, but bad in that the internal flow rate of the overflow is reduced beyond a critical point where settling occurs. If you were able to ensure that no settling occurred, I think the one of the primary advantages of a lowered section for standpipes would be achieved.

Although, being able to have a longer standpipe itself is possibly an advantage - although I'm not convinced of it providing the flow rate through the pipework is commensurate with a shorter pipe.
 

192k

Member
Nov 17, 2011
915
336
Northside Brisbane, 4017
I agree n0rk. The last tank I had was 1500mm long with an almost full length overflow and I understand what you are saying about the high volume/low flow areas that are inherent of the design.

The 3 most successful tanks that I have seen in person (Geoff, Tone & Pete's) all have internal overflows that are proportionate to the physical size of the standpipes and all 3 of those tanks achieve adequate surface skimming to help provide healthy and thriving conditions.

Another aspect to consider is where my stream pumps will be placed - I am hoping to have them as close to the surface as practical and this has an impact of with the full length overflow. They tend to slosh around when the pumps are pulsed on a high setting.