Looking for an old thread

[BPKlein]

Hello,

Years ago there was a thread running with pics of someone's overflow system. The system was basically two bulkheads drilled in the left and right upper corners of the tank. Between the bulkheads was a horizontal PVC pipe that had a slit cut in it. Surface water would drain into the slit and out the two bulkheads into the sump. Rotating the horizontal pipe could change the level in the display tank.

If anyone can point me to that thread, or just talk about the idea here, that would be great.

Thank You,
Bryan

 

[uncleof6]

There are actually a ton of threads that bring up or mention this method, usually along with the DIY PVC overflow concept. These methods will drain water out of the tank, however in short, they do not work as advertised, and the physics say they cannot.

There are two requirements with an overflow system. The first of course is to drain water out of the tank, the second half of the system. The first half of the system is to provide surface skimming/surface renewal, two essential functions for marine systems. Combining the two functions means that neither function will be done well.

These drain systems operate on the same principles as the durso stand pipe, even though the configuration is different. In order to provide the first essential function of the 'overflow' system, the flow rate of the system has to be low enough that the slit will pull the surface layer of water out of the tank. This means that air will be sucked into the drain, and create all the issues that are fueling the search for better drain systems.

If the flow rate is such that these problems do not exist, the 'slit' would have to be submerged below the water level, so it does not suck air. Of course, this would provide no surface skimming/surface renewal, and would not be safe (operating as a siphon system.) Power heads cannot be used to mitigate this failure, as power heads will mix the 'organic slick' back down into the tank, rather than sending it to the skimmer.

The conclusions reached by those familiar with the physics underlying both designs (slit pipe/diy pvc overflow) is that these devices are fine for very low flow systems (lower than what marine systems need,) but are not practical for meeting all the needs of a marine system. There are claims to the contrary, but the fallback is the physics, which say they do not and can not function as advertised. You can't beat the physics. With all the shortcomings and problems associated with the oveflow/durso system, it is still far superior to the 'slit pipe' and 'diy' (snakepit) pvc overflow.

 

[BPKlein]

Thank You for the information. I am only familiar with the overflow/durso style. This is one reason why I was looking for this article. I thought the thread mentioned stand up air holes in the top and at the ends of the horizontal pipe. Basically constructing a horizontal durso system.

I am in the very beginnings of planning a new tank, and I'm trying to decide the overflow so that I can start making templates for the glass.

 

[mcgyvr]

don't do anything but a beananimal..no really.. BA only. Its just the best/proper way and it really is virtually failsafe and dead quiet.
http://www.beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system.aspx

 

[BPKlein]

I am considering that route also. Thank You for the information.

 

[uncleof6]

Thank You for the information. I am only familiar with the overflow/durso style. This is one reason why I was looking for this article. I thought the thread mentioned stand up air holes in the top and at the ends of the horizontal pipe. Basically constructing a horizontal durso system.

I am in the very beginnings of planning a new tank, and I'm trying to decide the overflow so that I can start making templates for the glass.

Unfortunately, that would only be an attempt to beat the physics, which you will not be able to do. Much the same as the 'difference' between a durso and a stockman modification. In this case, however, you are not changing the location of the air inlet, rather allowing more in into the system. The more air in the system, the less water the system will handle. My suggestion is to A) run a standard durso overflow system, if you are going to run very low flow, or B) run a siphon overflow system, to accomodate more reasonable flow rates.

If you are planning on drilling the tank, there is no point in doing anything other than a 3-pipe siphon system aka: Bean's design, with a C2C overflow.

 

[SGT_York]

Just another point, while the horizontal slit may work with very low flows, that would be a maintenance nightmare always needing to keep it clean, snails could get the outside clean but the slit itself would always be getting fouled up.

A Coast 2 Coast overflow looks complicated it is actually fairly easy to DIY and there are several places to buy them from. With a new tank there really is no reason to not use a Bean Animal drain.

 

[mcgyvr]

Don't listen to these guys.. Do a beananimal instead. :wildone:

 

[BPKlein]

Thanks for all the help folks.