Silent and Failsafe Overflow System

[jimnrose]

Beananimal, I built my overflow box and plumbing just as your recommended and the system is silent with good flow. The only concern I have is that the siphon standpipe has no flow either at startup or during the run phase. Should I convert it to a second open channel? My hardware is a 125 gallon display with the sump on one side with the sump water level 8" below the display. The pipes are 1 1/4", all valves are wide open & the pump is putting out around 900 gph (Quiet one 4000). BTW it takes about 3 minutes before the system reaches equilibrium at start-up. [If it helps, the overflow box is 4 1/4" wide x 4" deep x 23 1/4" long]
Thanks for all your time and technical direction. Jim

[BeanAnimal]

Originally Posted by jimnrose

Beananimal, I built my overflow box and plumbing just as your recommended and the system is silent with good flow. The only concern I have is that the siphon standpipe has no flow either at startup or during the run phase.

That means that you have the output submerged too far into the sump and/or the siphons standpipe is higher than the open channel.

Should I convert it to a second open channel?

That would be a standard durso setup. If it is quiet enough and stable enough for you then sure...

My hardware is a 125 gallon display with the sump on one side with the sump water level 8" below the display.

Below the display surface or below the display itself? What is the total distance from the water level IN the overflow box to the surface of the water in the sump? That is the "head" on the siphon.

The pipes are 1 1/4", all valves are wide open & the pump is putting out around 900 gph (Quiet one 4000). BTW it takes about 3 minutes before the system reaches equilibrium at start-up.

I am not sure I understand? If there is no flow going through the siphon standpipe, then there is no equilibirum to wait for. Open channel flow is open channel flow.

What makes you sure that there is no flow in the siphon standpipe?

Are the standpipes through the back of the overflow or the bottom?
How far is the siphon standpipe submerged in the sump during normal operation?

[BeanAnimal]

Originally Posted by yoki32

Hi,

What size of the hole should I make for the 1/4 MPTF John Guest fitting and also what size tap bit should I use to thread it?

Thanks

You want a 1/4 MPT tap and a 7/16 drill.

[PowermanKW]

Many of these done on a external overflow? I have a Herbie now, but will do yours on my next tank. Not sure about a Calfo overflow, or a external. Anything I should consider?

[BeanAnimal]

Yes, plenty of folks are using the system on an external box.

Internal or external... there are pros and cons to each. Without knowing what your plans are, it would be hard to give advice. They both work the same with regard to function. The internal takes up some space in the tank but is easier to implement. The external takes a bit more thought and work, again depending on the type of tank and other parameters.

[yoki32]

Hi Bean,

I think I may have purchased the wrong John Guest fitting. On the bag it mentions 1/4" x 3/8 nptf? Is that the right fitting? If so, I don't get why I need a 1/4 tap..shouldn't it be bigger than 1/4? I'm confused...please help.

[yoki32]

This is the fitting that I'm talking about...

http://www.aquacave.com/john-guest-1...gray-1650.html

[BeanAnimal]

You need a 3/8" NPT tap
The drill size would be 9/16"

I thought we were talking about 1/4" NPT threads in the previous post.

[yoki32]

Hey Bean, ok the inside diameter hole measures 3/8" and the outside diameter hole including the thread is 5/8". Shouldn't the drill size be 5/8" and tap bigger than the hole size? I need to screw the fitting inside the hole right?

[BeanAnimal]

Originally Posted by yoki32

Hey Bean, ok the inside diameter hole measures 3/8" and the outside diameter hole including the thread is 5/8". Shouldn't the drill size be 5/8" and tap bigger than the hole size? I need to screw the fitting inside the hole right?

You need a 3/8 NPT tap for a 3/8 pipe thread. 3/8 NPT pipe has an O.D. of 0.675". (just over 5/8 of an inch). The 9/16" drill will leave enough material for the tap to cut threads into.

[yoki32]

ok i'll try that. I'll drill the PVC cap with a 9/16" drill bit and tap it with 3/8" and then will try to screw the JG fitting in the hole. Thanks Bean, appreciate your patience and all of your help

[PowermanKW]

Originally Posted by BeanAnimal

Yes, plenty of folks are using the system on an external box.

Internal or external... there are pros and cons to each. Without knowing what your plans are, it would be hard to give advice. They both work the same with regard to function. The internal takes up some space in the tank but is easier to implement. The external takes a bit more thought and work, again depending on the type of tank and other parameters.

No sweat. Thanks. I'll do more research. Don't really know what way I'll go at this point either.

[BeanAnimal]

Let us know when you get a better idea of what you want to build.

[jimnrose]

Beananimal, boy you have patience. Here goes:
the bulkheads are coming out the back (on the same horizontal plane).

the siphon & emergency caps are at the same height (6" above the tee cl) but the open channel is 4 3/4" above).

the siphon standpipe is 7" below the sump water level.

The o/f box is 1 3/4"below the display level and the inlet section of the sump is 8" below the display but the return section is 11" to 12" below the display. The sump pump has a 11" to 12" head. The drop from the o/f box to the inlet section of the sump is 6 3/4".

I'm nervous not having any flow thru the siphon standpipe. The system is running quiet and keeps up with the pump but not having two operating standpipes is unreliable.

P.S.I tried filling the siphon end cap with plumbersputty to bring the cavity down to the open channel cap but that didn'tresult in any change in flow.

I'll keep at it & would like any ideas you may have. Jim

[BeanAnimal]

Thoughts:

1. The siphon standpipe is submerged way too far. It should only be 1" or so below the water surface during normal operation.
2. The cap on the siphon standpipe MUST be air-tight. I prefer to use a threaded cap with a dab of teflon paste.

What makes you sure the siphon standpipe is running dry? The level of the "caps" does not make a difference

[jimnrose]

The sump water level is only 5"below the tee/bulkhead center. If I cut the standpipe at 1" below the sump water level then I'll be eliminating the valve. I guess I could add reducers at the end of the pipe if adjustment is needed.

The caps are air tight by using teflon tape and snugging down on the turns.

I put my hand under the pipes, after noticing the water seemed to be coming only thru the open channel.

I'll double check on the cap seal & cut off the standpipe 1" below the sump water level.

Thanks AGAIN. Jim

[tat2shawn]

on my system, being an internal overflow, What would the optimal drop the water should fall over the weir. Im guessing I can adjust it by making the PVC shorter or taller.

[BeanAnimal]

Originally Posted by jimnrose

The sump water level is only 5"below the tee/bulkhead center. If I cut the standpipe at 1" below the sump water level then I'll be eliminating the valve. I guess I could add reducers at the end of the pipe if adjustment is needed.

The caps are air tight by using teflon tape and snugging down on the turns.

I put my hand under the pipes, after noticing the water seemed to be coming only thru the open channel.

I'll double check on the cap seal & cut off the standpipe 1" below the sump water level.

Thanks AGAIN. Jim

Your adjustment valve is below the water line in the sump? That is certainly not ideal

Can you post some photos? Without a valve, the system will not be adjustable.

[BeanAnimal]

Originally Posted by tat2shawn

on my system, being an internal overflow, What would the optimal drop the water should fall over the weir. Im guessing I can adjust it by making the PVC shorter or taller.

The less fall, the less chance of noise. I would shoot for an inch or so. Becuase your standpipes are vertical through the bottom of the box, you have the luxury of adjusting them to suit your needs

[jimnrose]

Beananimal, you ask for pictures but that's another task I havn't tackled.

The sump is adjacent to the display (display is a see thru but the sump is in a cabinet (wall to wall cabinets) adjacent to the display tank but 7" lower. The bulkhead fittiing is 2.5" from the top of the display and the 1.25"tee is another 2" drop. There is a 3.5" of pipe to the valve & the water level is 3" below the tee. I could cut off the 3.5" pipe 1" below the tee (to remove the valve) and add a coupling (but not welded) to bring the pipe 1" below the water level. If I need a valve I could reinstall one but it would only be about 1.5" higher than the present one.

Hopefully I relayed the set-up OK. Guess I better learn how to use photobucket before long BUT after I get this system flowing like a silent river.

Take care, Jim

[jimnrose]

Beananimal, AGAIN you have come thru. I cut off the siphon standpipe ( which eliminated the valve) and the flow is now in the siphon pipe. There is no flow control & the water level is only 1.5" in the o/f box ((about only a 1/4" before the elbows start drawing water). I was going to use reducers on the siphon pipe to cut back flow but decided to try increasing the siphon tube (greater than 1" below the water leve)l & it works.

Another one of your overflow systems in use. I wonder how many are in operation at this time.

THANKS, Jim

[jimnrose]

Beananimal, I got it; bye gollie, I got it. It wasn't the depth of the siphon tube but the reduced area thru the gate valve. When I eleminated the gate and shortened the siphon pipe to 1" belw the water, the flow was finally in the siphon pipe but the water level in the o/f box wasn't high enough. I went back to the siphon tube being 6.5" below the sump water level (but w/o the valve) and there was no change from the 1" depth. I then looked inside the valve and the tube diameter is 1.125" diameter (down from 1.5"). Thats a 45% reduction in area. So I added a 1.5" 90 elbow to the 1" siphon pipe & the water level in the o/f box is now exactly where I want it (2.5"). The start-up is great [open channel does it's job and the emergency elbow doesn't come into play which means there is extra reserve].
In my case where there is a very short drop from the o/f box to the sump water (6/5") the flow rate is very sensitive to pipe area & direction.

That's it for me taking up your time.

Until next tim, enjoy. Jim

[BeanAnimal]

Your observations are correct, let me help explain what is going on (in case you or others are interested.

The flow rate of the siphon is directly proportional to the head on the siphon. The positive head is the distance between the suction pool's surface and the surface of the discharge pool. That is, the the distance between the surface of the water in the overflow box and the surface of the water in the sump.

Restrictions in the plumbing (friction) and turbulence caused by the plumbing subtract from the overall head.

In your setup the actual vertical head is small enough that slight changes in pipe configuration contribute a significant amount to the total head of the system.

I am curious to see how the long term stability of the siphon level plays out. I suspect you will be fine, as the system is pretty much set and forget. You have set it via manipulating the pipe configuration instead of a valve.

I am glad the system is working as designed

[JTL]

I just had a shrimp go down the full siphon and mess up the flow until he got crushed by the gate valve and passed through as I was opening and closing the valve. Is anyone putting something over the intake pipes to keep this from happening? I liked that shrimp.

[jimnrose]

I'm new at this but have the elbows 1/8" above the o/f box bottom and put 1/8" groves `/4" high along the circumference just like the photos beananimal shows. If a shrimp got in the o/f box, it probably wouldn't squeeze the groves. Jim