herbie drain size for uk (metric) overflow

daniel smith · 02/11/2018, 09:40 AM

Hello, I am currently setting up a reef tank with dimensions of 36" x 45" x 14"(h) which is hallway sized between your (USA) 30b and 40breeder. Anyway as I have only ever had dursos on my tanks and the herbie on the last was a happy accident when I added a valve to one standpipe and raised the other with a socket. So I am designing a herbie overflow for the first time and going on the fact that I will be using an eheim 1250 for return which is 317 gph , I am think would I be ok using a 20mm (metric) drain which has an internal diameter of 0.669291 inch so a bit bigger than half inch. I have used bean animals calculator which says 0.669291 has capacity of 446 gph which is obviously more than required. Am I pushing it with this or should I use 25mm which I ID 0.866142 (a touch bigger than three quarter US). I have seen ,or sorry read about USA tanks using 0.5 inch for main and three quarter for emergency so I am assuming I should be ok just using UK metric versions.

daniel smith · 02/11/2018, 09:43 AM

Oh yes, the overflow will have a 12 inch toothed weir and be covered and the main drain will have a strainer to keep out little snails and will be controlled with a gate valve.

02/11/2018, 09:40 AM	#1
daniel smith Registered Member Join Date: Jul 2005 Posts: 30	herbie drain size for uk (metric) overflow Hello, I am currently setting up a reef tank with dimensions of 36" x 45" x 14"(h) which is hallway sized between your (USA) 30b and 40breeder. Anyway as I have only ever had dursos on my tanks and the herbie on the last was a happy accident when I added a valve to one standpipe and raised the other with a socket. So I am designing a herbie overflow for the first time and going on the fact that I will be using an eheim 1250 for return which is 317 gph , I am think would I be ok using a 20mm (metric) drain which has an internal diameter of 0.669291 inch so a bit bigger than half inch. I have used bean animals calculator which says 0.669291 has capacity of 446 gph which is obviously more than required. Am I pushing it with this or should I use 25mm which I ID 0.866142 (a touch bigger than three quarter US). I have seen ,or sorry read about USA tanks using 0.5 inch for main and three quarter for emergency so I am assuming I should be ok just using UK metric versions.

02/11/2018, 09:43 AM	#2
daniel smith Registered Member Join Date: Jul 2005 Posts: 30	Oh yes, the overflow will have a 12 inch toothed weir and be covered and the main drain will have a strainer to keep out little snails and will be controlled with a gate valve.