There are 2 advantages of using a Durso standpipe for the overflow. It is the cheapest as it only requires one bulkhead and drain line, and it can be used with a siphon from the tank to the overflow box in applications where a new bulkhead is not possible or warranted. Plus, you can use it on tanks that only have one return in the overflow. The key principle is that you can adjust the airflow in the vertical pipe to quiet the flow and prevent a siphon from developing. This allows a consistent flow. However, the larger the pipe, the noisier it will be. And if it ever clogs, there is no backup. Of course, there is no reason an emergency standpipe cannot be used in addition. In other words, you tune the air flow in a Durso standpipe and tune the water flow in a Herbie.
Basically, the typical Durso standpipe is an upside-down U with the water entrance under water. Having the entrance under water helps muffle the sound. The air vent is at the highest point of the tube. It usually has some form of adjusting the holes size to control air flow. The vertical standpipe often necks down just above the standpipe (At this time I don’t know if it helps flow better or if PVC DWV or ABS fittings are used which are cheaper and are better for slip fitting use, but only come in the larger sizes). Some claim that good air control can make this a quiet system.
Of note this pipe as a secondary drain, or a modification that can allow a siphon in emergencies (high water levels) and a Herbie overflow standpipe as a primary drain is part of a bean animal overflow system.
If you have pictures of your Durso, please post and provide any comments on what you think others should know.
https://blog.marinedepot.com/2018/04/we-speak-with-richard-durso-creater-of-the-durso-overflow-about-how-he-got-into-reefing-and-giving-back-to-the-aquarium-hobby.html
https://www.dursostandpipes.com/
Here is the diagram from Marine Depot showing the basic system.
Basically, the typical Durso standpipe is an upside-down U with the water entrance under water. Having the entrance under water helps muffle the sound. The air vent is at the highest point of the tube. It usually has some form of adjusting the holes size to control air flow. The vertical standpipe often necks down just above the standpipe (At this time I don’t know if it helps flow better or if PVC DWV or ABS fittings are used which are cheaper and are better for slip fitting use, but only come in the larger sizes). Some claim that good air control can make this a quiet system.
Of note this pipe as a secondary drain, or a modification that can allow a siphon in emergencies (high water levels) and a Herbie overflow standpipe as a primary drain is part of a bean animal overflow system.
If you have pictures of your Durso, please post and provide any comments on what you think others should know.
https://blog.marinedepot.com/2018/04/we-speak-with-richard-durso-creater-of-the-durso-overflow-about-how-he-got-into-reefing-and-giving-back-to-the-aquarium-hobby.html
https://www.dursostandpipes.com/
Here is the diagram from Marine Depot showing the basic system.
