Dorso ? fine tuning

[saltwaterexotic]

Has anyone ever used a small needle value or something to adjust their Durso drain pipe instead of drilling and up sizes holes on cap to fine tune it?

My drain is 1 1/4" sch 26 pipe and sch 40 fittings on a sch 80 1" bulk

 

[uncleof6]

Sure I have, it does not work any better than anything else. The only way to "tune" a durso, or any open channel drain, is to slow the flow till the pipe is less than 1/4 full of water. Any more than that, and the standpipe becomes proportionally worse with the increase in flow rate. < 1/4 full is described as the laminar flow rate. (Water flowing on the walls of the pipe, with CALM air in the middle.) Increasing the amount of air (enlarging the hole,) reduces the amount of water that can be in the standpipe, and vice versa. Exactly the opposite of what most people think. However, the pipe size determines what "1/4" full is, and thus the laminar flow rate. For 1" pipe that is ~50 gph, and for 1.5" pipe that is ~350gph. 1.25" is rather uncommon (in actual use anyway) so I do not have a benchmark for it. I would venture a guess at ~200gph. Dursos are low flow devices, and were never intended for marine system flow rates.

There are lots of proclaimed quick fixes floating around, but none of them really fixes the issues. The only thing that actually fixes the issue is slowing the flow rate to the laminar flow limit. (until the problem stops.) All of the fixes involve lowering the flow rate, whether it is realized or not. The only other solution is to convert to a siphon system. In "tuning" dursos, the higher the flow is tweaked, by playing with the air, the more there is a risk of plugging, and the more unstable they become. You are further limited flow wise, by the 1" sch 80 bulkhead (smaller inside diameter than sch 40, or ABS bulkheads.)

BTW, there is no such thing as sch 26 pipe. There is sch 40, sch 80, cls 200, SDR-21, (being the most common,) and other SDR pipe. The thinnest SCH pipe is 40 however. Sure it is not SDR-26?

 

[saltwaterexotic]

Thanks of the reply. I'll have to dbl check but it's the thin walled sch pipe. I would have went with a Ba but not enough room in a 5x6 tower overflow

 

[saltwaterexotic]

fine tuning

fine tuning

I was planning to put this 1/4" tubing bulkhead on bottom of my tank in overflow and tapping the Durso cap and putting the tubing down the inside of overflow box through bulkhead and use this needle value for fine tuning would this work well ?

 

[saltwaterexotic]

jg 1/4" tap fitting on cap

jg 1/4" tap fitting on cap

cap fitting

 

[saltwaterexotic]

precision needle valve

precision needle valve

adjustment valve

 

[saltwaterexotic]

not looking for better just looking for same control other than up size or down size of hole to adjust under sump I want the tubing to go down in overflow so it's not seen as this is a center tower overflow just wondering if the bulkhead would work and not leak with the slip in fit of tubing

 

[uncleof6]

Thanks of the reply. I'll have to dbl check but it's the thin walled sch pipe. I would have went with a Ba but not enough room in a 5x6 tower overflow

Depends on where you got the pipe. If at a big box type store, or similar it is going to be cls200, if at a irrigation supply or similar it will probably be SDR-21. SDR-26 isn't common even with specialty suppliers.

not looking for better just looking for same control other than up size or down size of hole to adjust under sump I want the tubing to go down in overflow so it's not seen as this is a center tower overflow just wondering if the bulkhead would work and not leak with the slip in fit of tubing

There are only two ways to "fine tune" a durso, or other open channel modified standpipe, one is by adjusting the valve on the pump output, which controls the flow rate through the system, and consequently the flow through the drain system. This is how every aquarium drain system is adjusted. Two is to vary the pipe size/bulkhead combination; in most cases this can be a bit inconvenient.

The durso was invented to solve one problem: eliminate the water fall to the bottom of a corner overflow. The inventor, Richard Durso, by his own admission, had no idea of the physics governing the operation of the design. The physics are written in stone, and you cannot beat the physics. If the physics could be 'fine tuned' out of the durso, there would not be such a wide scale search for a better solution, and siphon systems would still be a rather secretive art. I am not trying to convince you to convert to a siphon system, rather explain how your drain system actually works, why it is limited, and why your proposed solution is best left as an idea only.

All the gimmicks/modifications, dealing with airflow, with these type of standpipes, still produce noise, and the quieter they are, the less stable they are.

I think you will benefit by reading the first few paragraphs of this article where it deals with standpipe basics. Again, I am not steering you to a siphon system (although that is the only real solution to durso standpipes.)

http://www.beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system.aspx

In terms of your propsed needle valve setup, I think you are getting carried away, overthinking it. To adjust how much air gets in the standpipe, you simply need a valve on top of the standpipe, rather than all the fancy tubing, down through the bottom of the overflow, to needle valve. Remember, the more you overthink the plumbing, the easier it is to stop up the drain.

Thus: (the air tubing is completely useless in a normal durso setup, it accomplishes nothing, serves no purpose.) I am not recommending that you do this, however.

 

[saltwaterexotic]

being a open top tank viewed 360 I didn't want a valve on top that's why I asked of I can run tubing back down to a valve hiding the valve and only showing a small bit of tubing from top. Thanks I will read up on the link you suggested.

 

[uncleof6]

I run rimless tanks exclusively, they are all open top or hoodless. Such things as the plumbing are part of the game. There is no getting around it. There is no point to doing what you want to do anyway, however. It will simply make the system less safe, but no less troublesome.