getting water to the sump?

  • We are currently upgrading MFK. thanks! -neo
71586overflow-print-med.gif

Let's focus on the left hand side and forget the right. If we do this, it's a simple pvc overflow. The reason that it has two sides is for stability and redundancy.

Focusing on the left hand side, the water level is governed by two parts A and P. as the water flows over the top of A it raises the level of the water in G flowing into P. The check valve is a one way air valve to allow you to suck the air out of the pipe to create a vaccuum in the pipe. This allows for the siphon to continue even after a power outage. You simply have to make sure that the water level you want and A and P coincide. You must also make sure that the pipe is air tight. using pvc glue makes this much easier. When you attach your air valve you can seal it with silicone
 
If you do not have A and B you will lose your siphon if the water falls below the intake. I like to have A be at the same level or very near the same level as P. that way when the water rises over the intake it immediately begins to flow down the drain pipe.

The problem with your overflow is that there is nothing there to prevent loss of siphon. thats why there is an overflow box on the inside of tanks, if the water drops below that line there is still water in the boxand in the pipe. when water begins to flow over that box again the siphon continues. B and A work to replace the overflow box. if the water drops below A, everything stops.. once it rises above A, it flow s down through again and the siphon begins again. this is because we make sure the water stays in the pip. thats why we have 2 u's and not one.
 
I guess the easiest way to describe the problem with the design is to give you a for instance...

If the pump shut off in the sump, it is no longer returning water to tank. God forbid the air hole in the standpipe gets plugged because you in effect will have an unstoppable siphon that will drain the wank down to however deep the bottom of the pipe is. this will overflow your sump and create the always happy "Instant Wet Floor".

Secondly, overflows are usualy designed as skimmers. Taking water from the top of the column/surface. this has many benefits to the gas exchange in your tank.

Having A and B are simple insurance measures as well as smart measures for filtration. By no means am I saying the pipe you made won't work. it will, and it may work well.. it just has the potential for a few problems. Besdies, skimming is a pretty good thing. :D
 
brown bag your lunch for a couple of days and then get the stuff to drill the tank already... the 1" fittings alone have surpassed the cost of bulkheads, and a diamond hole saw is less than $10.00

All to often people try to reinvent the mousetrap, when it's not needed...there are reasons for overflows, just go with the tried and trued, and you won't have to ask why the "new and improved" didn't work...
 
it works! it cant drain the tank because when the water gets to below the "T" the siphon equals out and quits flowing. the "T" is the outlet of the siphon (the end of the hose). if your pulling water from the top of the tank or the bottom the siphon is really only what is above the water line, where gravity stops pulling it down. so once the water line is even with the "T" the pressure is equal. the "T" and the line to the sump are just an overflow, they have nothing to do with the siphon effect at all.
 
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