overflow g.p.h

fishbait

fishbait

I found Nemo
i made a homemade overflow last night out of 3/4 pvc. i gave it a test run into the rubbermaid tub that i will be temporarily using for a sump. of course it seemed like this thing flowed 10,000 gph. does anyone know appx. what it would flow? it dumped about 5 gallons of water in about 10 to 15 seconds.
 
Seems like I remember seeing a calculator on the net once that allowed you to put in your desired GPH, and it would spit what size pipe you need. I haven't been able to find it yet, but I'll keep looking for you.
 
that is a very neat calculator john. im not very good at excel. but if i figured everything right i have a little over 1000 gph with 3/4" pipe.
 
argh! i typed a post for 30 minutes yesterday and for some reason it didn't post. i'm not sure if that is correct. but, i'm not using an actual box. it's just a piece of pipe with 2 90's stuck in the water. if i decide to use it i will put some type of screen over it so it won't suck up my critters. or build a box on the inside so it will skim off the top of the water. the question that i typed yesterday was, does the overflow box slow down flow? going through the u-tubes and into the box in the back, over baffles and then down the pipe. would it flow faster with just the pipe. i'm not very good at using excel. so i doubt that i figured it right. because it asked for square inches of flow area. so i put in 1/2 inch. which is what i guessed 3/4 pipe to be.
 
I'm a little confuse in what you are asking.How fast and how much water flows down to the sump depends on much water is return to the DT.Can you post pics of what you are trying to do.
 
1 inch train is usually between 600-800 so my guess would be between 400 - 600.

You can always get a little more, but the above will keep your floor dry :).

Brandon
 
reef, what i was doing was just sticking a piece of pipe, without an overflow box into the water. i put two 90 degree elbows on it like you normally would on a return line. and started a siphon into a rubbermaid tote to see how much it would flow.
 
i was just wondering if it would flow more, or the same like this. rather than using the typical overflow box. it just seems like there is a lot less for the water to go through before it makes it to the sump. possibly making a higher flow rate?
 
fishbait said:
reef, what i was doing was just sticking a piece of pipe, without an overflow box into the water. i put two 90 degree elbows on it like you normally would on a return line. and started a siphon into a rubbermaid tote to see how much it would flow.
Click to expand...

I understand what you are trying to do now.The only thing I can think of is to try it for awhile and see how it goes.Honestly,I never seen it done like that before.I seen it like Bobby's thread where a tank was drilled near the top with a 90 degree elbow(pvc) turn upwards to drain the water near the surface.It sounds like it would be noisy,maybe not.Good luck with the project.
 
Fish:

If i understand what yoru asking that would require your pump perfectly match the GPH of the siphon you start.

If not the siphon will eventuall suck so much water out of the tank it will then suck air breaking the siphon then the pump will flood the tank. Or the sipon wouldn't be enough GPH and the pump would eventually overflow the tank.

You either need to drill a whole in the back of the tank and use an overflow like that or get an actual overflow box.

Hope I understand what your asking and have given you the correct answers.

Brandon
 
i have never had a sump or overflow. so please forgive me if i sound stupid. but wouldn't i have the same problems balancing flow with a overflow box? shouldn't i be able to control it with a ball valve? as far as noise i dindn't hear any slurping or gurgling noises. the pipe goes about 2 inches into the water so it doesn't suck any air. and it is also pointing downward so it doesn't create a little tornado at the surface of the water.
 
You don't really need to "control" it or make sure that they are equal... You just need to make sure that your return pump does not flow faster than your overflow box. If your return pump pumps more water than your overflow box drains, then your tank will overflow. But your overflow box will only drain as much water as the pump puts back. Look at it this way, your return pump will do all the controlling for you, because the overflow box will only fill up with water and send water to the sump as fast as the return pump can send it back to the main tank. As long as the return pump is slower than the overflow box, there won't be any floods. Be sure to make sure you take care of the potential for back siphoning too, either by putting in a one way valve or drilling some holes in the pipes near the surface of the water...
 
ah, i see! thanks biff. i didn't know that the overflow box functioned like that. so it WILL help balance out the flow. i thought that once the siphon started they pretty much flowed whatever they were capable of. so it the power goes off will the overflow box stop flowing when the pump starts? or will they drain down until the siphon breaks?
 
What they're capable of is the maximum they can flow. The speed of the return pump will control the water level in your tank, and only when the water level goes above the lip of the overflow box will water flow through it to the sump. So if the return pump is working slowly, it will take longer for the water level in the main tank to rise, and longer for the water to flow through the overflow box.

If the power goes off, the overflow box will continue pulling water out of your main tank until the water level gets below the lip of it. Then it will lose siphon, so if the power comes back on, the return pump will shoot water back into the main tank, but the overflow box will not move water back to the sump. To prevent a flood, you should make sure that you either keep enough "space" at the top of your main tank to accomodate all the water in your sump (even then, your return pump will run dry -- bad news). A better option is to use a little airlifter pump attached to the overflow box that will automatically restart the siphon when the power kicks back on. The one I have ran about $8 I think, and I've tested it out several times, when the power goes off and comes back on, the airlifter automatically restarts the siphon and gets the overflow box going again.
 
thanks for clearing all that up for me. i have looked at the cpr overflows and wondering why they needed the aqualift pump. now i know.:)
 
Not trying to hijack your thread Fish.
Biff or Jhn,Would you have to drill the siphon tube to install a fitting for the aqua-lifter suction line,or could you just stick it inside the tube?
I been playing around with that in my head,and also thought about putting a float switch to shut the power to my pump off if the level in my sump got to low.
I really dont want any more wires around my tank if I can get out of it.
 

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