Durso - Why Tee + cap?

[MjOB]

When making a Durso, why is it:
Pipe - Tee - (Middle) - street ell - (Top) - cap and drill hole in cap
And not just
Pipe - Street Ell and drill hole in top of street ell?

I have a modular marine 3000gph low profile overflow.
When trying to follow for what height to set my Durso, with the tee in place, the cap goes above the overflow and I can't put the lid on the overflow.

I currently have attempted Tee - ell with 1.5" Sch 40 PVC and there isn't enough room for the ell, as it hits both the bulkhead from tank to overflow, and the back wall of the overflow. This has prevented the gasket from forming a seal and causing a leak in the bulkhead. So, I need to make a change - going to try and use DWV street ell to see if its smaller wall will be all I need. Have to make another run to the store for that though. If that doesn't work I'll just dip down to 1.25"

 

[ZombieEngineer]

I did mine like this with street elbows. The full siphon one you could use a slip strainer instead if you want the extra room. The way mine is designed, I had to lower the full siphon and drill a hole in that too for it to reliably restart siphon after restart (mine does this automatically 3 times a day so super important that it restarts full siphon reliably.

I hindsight I would have been better off with the strainer, but I don't want to take the canopy off to redo that part now. I will probably switch it the next time I need the canopy off anyway.

 

[MjOB]

I did mine like this with street elbows. The full siphon one you could use a slip strainer instead if you want the extra room. The way mine is designed, I had to lower the full siphon and drill a hole in that too for it to reliably restart siphon after restart (mine does this automatically 3 times a day so super important that it restarts full siphon reliably.

I hindsight I would have been better off with the strainer, but I don't want to take the canopy off to redo that part now. I will probably switch it the next time I need the canopy off anyway.

Are you saying you wish you'd done a slip strainer instead of the street elbow on your primary / full siphon?

But using the street elbow without a Tee with a hole in it works well for your secondary?

 

[ZombieEngineer]

Are you saying you wish you'd done a slip strainer instead of the street elbow on your primary / full siphon?

But using the street elbow without a Tee with a hole in it works well for your secondary?

Yep.

The secondary is straight pipe -> normal elbow - street elbow. Drilled a hole in the street elbow and stuck a piece of tubing in it.

 

[MjOB]

Glad to hear that works. It has looked like in photos of others that's all they've done too (although I haven't seen the tubing before - what's the purpose of that?) but any "How to" / videos always use the Tee.

 

[ZombieEngineer]

Glad to hear that works. It has looked like in photos of others that's all they've done too (although I haven't seen the tubing before - what's the purpose of that?) but any "How to" / videos always use the Tee.

The tube is to prevent it from becoming full siphon unless the water level rises high enough that the emergency drain is in effect.

 

[KStatefan]

The original write up on the BeanAnimal design https://beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system/

There are a number of ways to make a three pipe drain system work. The Innovative Marine EXT tanks just use straight pipes.

 

[MjOB]

Modifying it a bit, I can get it to fit like so:

With a schematic (modified form of Marine Depot's Bean Animal description)

Is it alright to have the secondary and primary drains pulling from the same location (the middle) in the overflow? Is it better to have it spaced out (ie, primary on the far right, secondary far left?)