Weir???

jwccwj · 09/05/2007, 08:34 AM

HI,I was wondering why some external overflows are deeper than others,some people have there overflow box only a few inches deep while others have them almost the full depth of the tank.I think they call the shallower one a weir,are the any advantages to a shallow external overflow box as opposed to full size one??There will be 3 or 4 dursos in the overflow box,does it matter if only the top of the durso is in water with the lower portion of the durso outside of the bottom of the overflow box??I hope this makes sense.

Jamie.

murfman · 09/05/2007, 08:54 AM

Jamie, my 1st tank had two full sized overflows with 1 Durso and 1 return per overflow, going through the bottom of the tank. When I built my new tank with the closed loop, I had an overflow built that is only 1/4 the depth of the tank. It has one 1" bulkhead draining to the sump/fuge.

I like the new design because, if I loose power, I only drain about 10 gallons or so into my sump where with the Dursos, I would drain about 20.

jwccwj · 09/05/2007, 09:52 AM

Good point murfman,I never thought about a power outage,so would there be any other advantages to a shallow O.F?Does a smaller overflow mean less water can be drained?Would a larger tank say 240g require a full size overflow to get the desired gph to the sump or is drainage unaffected by the depth of the overflow box???

09/05/2007, 08:34 AM	#1
jwccwj Registered Member Join Date: Feb 2005 Location: Port Au Port,Newfoundland,Canada Posts: 405	Weir??? HI,I was wondering why some external overflows are deeper than others,some people have there overflow box only a few inches deep while others have them almost the full depth of the tank.I think they call the shallower one a weir,are the any advantages to a shallow external overflow box as opposed to full size one??There will be 3 or 4 dursos in the overflow box,does it matter if only the top of the durso is in water with the lower portion of the durso outside of the bottom of the overflow box??I hope this makes sense. Jamie.

09/05/2007, 08:54 AM	#2
murfman Registered Member Join Date: Jan 2004 Location: Colorado Springs Posts: 4,670	Jamie, my 1st tank had two full sized overflows with 1 Durso and 1 return per overflow, going through the bottom of the tank. When I built my new tank with the closed loop, I had an overflow built that is only 1/4 the depth of the tank. It has one 1" bulkhead draining to the sump/fuge. I like the new design because, if I loose power, I only drain about 10 gallons or so into my sump where with the Dursos, I would drain about 20.

09/05/2007, 09:52 AM	#3
jwccwj Registered Member Join Date: Feb 2005 Location: Port Au Port,Newfoundland,Canada Posts: 405	Good point murfman,I never thought about a power outage,so would there be any other advantages to a shallow O.F?Does a smaller overflow mean less water can be drained?Would a larger tank say 240g require a full size overflow to get the desired gph to the sump or is drainage unaffected by the depth of the overflow box???