Silent and Failsafe Overflow System

[ram1500]

Thanks for the advise on the bulkheads and drilling. Couple more questions.

Is the idea to get the downward facing elbows as close to the bottom of the overflow box? How important is the distance?

Using the 1" slip x slip bulkheads, does that mean the elbow and 1" pipe leading to the tee get glued to the bulkhead? I guess my question leads to the need to taking it apart for maintanance. If it's all glued together, that would be tough.

thanks
GUs

 

[afgun]

Thanks for the advise on the bulkheads and drilling. Couple more questions.

Is the idea to get the downward facing elbows as close to the bottom of the overflow box? How important is the distance?

Using the 1" slip x slip bulkheads, does that mean the elbow and 1" pipe leading to the tee get glued to the bulkhead? I guess my question leads to the need to taking it apart for maintanance. If it's all glued together, that would be tough.

thanks
GUs

You don't want the elbows too close to the bottom of the box as it could restrict flow. My 1 1/2" piping is about 1" from the bottom now, and that's about as close as I'd recommend taking it with that size pipe. When I added the screening extension I had to slightly re-tune my system.

I would not recommend gluing the pipe to the bulkhead; mine is a press-fit and seals pretty well. You are right about maintenance if you glue... bad idea.

 

[BeanAnimal]

If you feel like doing some math....

The area created by the distance between the bottom edge of the elbow should be at least (or greater) than the cross-sectional area of the elbow.

So for example: lets assume a 1.25" elbow with an inside diameter of 1.66"
The cross section area is .83" * .83" x 3.14 = 2.16 square inches

Instead of measuring the OUTSIDE diameter of the pipe, lets just use the inside diameter to make life easy for the next part. This will also add in our fudge factor to get a bit of extra spacing to account for surface tension, turbulance, etc.

We know that the circumference of the circle is 1.66" * 3.14 = 5.21"

So if we divide the needed area (2.16 sq in) by the circumference (5.21") we get
2.16" sq / 5.21" = .41"

So your elbow needs to be at least .41" off of the bottom to prevent a flow restriction. So .5" should be fine. Larger is not bad, but you need to consider snails getting sucked in. Guards are OK as well, but you need to consider what happens to a fish or shrimp that gets into the overflow. In the very fast current it will likely get sucked into the guard and perish. If it was open, it would end up happily in the sump with a free waterslide ride.

A lot of work for something that can be guessed at, but like most things in the physical world, there is an answer to the question that can be derived via math.

 

[RocketSurgeon]

I left plenty of room to be able to turn my elbows for ease of maintenance.

If I were to do it over again, I would use smoked glass and have a shorter box.

 

[TheFishMan65]

BeanAnimal, I might be wrong so please correct me but

Instead of measuring the OUTSIDE diameter of the pipe, lets just use the inside diameter to make life easy for the next part. This will also add in our fudge factor to get a bit of extra spacing to account for surface tension, turbulance, etc.

Don't you have to use the inside diameter. This means that as the water is going past the inner edge it will be at the same velocity as the water going down the pipe. If you used the outer diameter it would actually have to go faster. Wouldn't it? Or am I missing something on fluid dynamics?

If it was open, it would end up happily in the sump with a free waterslide ride.

Just a word of caution this only works if the valve is open enough to let the critter through.

Thanks

 

[BeanAnimal]

BeanAnimal, I might be wrong so please correct me but

Don't you have to use the inside diameter. This means that as the water is going past the inner edge it will be at the same velocity as the water going down the pipe. If you used the outer diameter it would actually have to go faster. Wouldn't it? Or am I missing something on fluid dynamics?

You are correct. In my attempt to make thing simple I overlooked the simple... Thank you for pointing out my mistake.

Using the I.D. of the socket fitting gives us a fudge factor, as the I.D. of the socket is a bit larger than the I.D. of the pipe it is connected to (in this case the I.D. of the rest of the fitting, bulkhead, etc.)

Just a word of caution this only works if the valve is open enough to let the critter through.

Thanks

Most fish and soft things have no problem with the valve.... hermits and snails are another story. I have been rather amazed at the fact that I have never had a fish harmed by being sucked though

On a very low flow system with a fairly tight valve, the flow will be lower and have less suction and also need less of a gap. In other words, it is all somewhat relative. On a high flow sytem with higher suction you need a larger gap and the valve will also be open more.

I lost a lot of astrea snails because they got stuck at the opening of the siphon overflow. I have since created an egg-crate barrier so that they can no get to the pipe itself.

 

[afgun]

I lost a lot of astrea snails because they got stuck at the opening of the siphon overflow. I have since created an egg-crate barrier so that they can no get to the pipe itself.

We have now had 3 fish in the overflow in 3 days. Not sure why they're so interested in it all of a sudden. So I bought some gutter guard and am going to attempt to keep the fish in the tank itself...

 

[TheFishMan65]

Interesting observation on the valve and fish. I had never had fish make it the far. knock-knock

Thanks Bean

 

[liz62]

Using Herbie method.


Maybe someone can help me? I just shut off all power sources to my tank and of course it began to drain into my Sump - problem is - it didn't stop draining!!

If I hadn't been standing right there to pull the siphon and emerg. drain lines out of the water in the Sump I think the whole tank would have drained out?

So what am I doing wrong? Should the drain lines in the Sump be out of the water at all times? This would be a heck of a noise draining into my Sump all of the time and kinda defeats the purpose of the whole Herbie way?

 

[rayn]

Shouldn't matter which method. Where are your drain lines located in relation to the water line? I wont quit draining till they are out of water to drain.

 

[rayn]

You don't want the elbows too close to the bottom of the box as it could restrict flow. My 1 1/2" piping is about 1" from the bottom now, and that's about as close as I'd recommend taking it with that size pipe. When I added the screening extension I had to slightly re-tune my system.

I would not recommend gluing the pipe to the bulkhead; mine is a press-fit and seals pretty well. You are right about maintenance if you glue... bad idea.

Well this could be some of my problem. I have the 1 1/2 pipe only about a half off the overflow. Maybe I need to tilt the 90° some.

 

[liz62]

Shouldn't matter which method. Where are your drain lines located in relation to the water line? I wont quit draining till they are out of water to drain.

That's what I don't get. The main drain is probably 3" below the teeth of the overflow. Both the siphon and the emerg. outputs are below the water level in the sump.

 

[CJBROWN]

Using Herbie method.


Maybe someone can help me? I just shut off all power sources to my tank and of course it began to drain into my Sump - problem is - it didn't stop draining!!

If I hadn't been standing right there to pull the siphon and emerg. drain lines out of the water in the Sump I think the whole tank would have drained out?

So what am I doing wrong? Should the drain lines in the Sump be out of the water at all times? This would be a heck of a noise draining into my Sump all of the time and kinda defeats the purpose of the whole Herbie way?

Is it the drains or the pump return that keeps flowing?

Mine is setup that once the pump is shut off the water level only has about a quarter inch to drain off before it can't flow over the wier any longer, maybe a gallon. The pump return has a 1/4" hole in the line right at the water level during operation. When it shuts down it drains back 'till the the hole breaks the siphon, about another gallon. I get about 2-1/2 gallons total drain back, have left room in the sump for that.

If your drains are noisy then you're not getting a full siphon going in your main drain line. If it's the second pipe, the durso style with the vented top that's making noise, then you have too much water going thru it. If you tune the siphon drain so it's taking 95% or better of your full flow then it won't make any noise either. Position the vent hose for it just below your full open drain to make it a full siphon in an emergency.

Maybe post a pic??

 

[liz62]

Is it the drains or the pump return that keeps flowing?

Mine is setup that once the pump is shut off the water level only has about a quarter inch to drain off before it can't flow over the wier any longer, maybe a gallon. The pump return has a 1/4" hole in the line right at the water level during operation. When it shuts down it drains back 'till the the hole breaks the siphon, about another gallon. I get about 2-1/2 gallons total drain back, have left room in the sump for that.

If your drains are noisy then you're not getting a full siphon going in your main drain line. If it's the second pipe, the durso style with the vented top that's making noise, then you have too much water going thru it. If you tune the siphon drain so it's taking 95% or better of your full flow then it won't make any noise either. Position the vent hose for it just below your full open drain to make it a full siphon in an emergency.

Maybe post a pic??

It is the drains that keep flowing - once I lifted the outlet pipes out of the sump it stopped draining. It is like I had to break the siphon on the main drain for it to stop draining.

 

[rayn]

Clbrown has a good point.

Water has to quit flowing into the overflow, then whatever can get in the drain will drain.

You said you pulled the pipes out of the sump. Was that rift or a mid type. Pulling them out of the sump wont stop the drain, just move where the water flows to.

 

[CJBROWN]

It is the drains that keep flowing - once I lifted the outlet pipes out of the sump it stopped draining. It is like I had to break the siphon on the main drain for it to stop draining.

That doesn't make sense. Regardless of what level the drain is in the sump, it will have nothing to drain once water quits flowing over the teeth of your weir. Where is it getting its water when you shut off the pump?


EDIT: the only thing I can think of is that you're using a siphon drain over the top and into the main tank?
When your pump stops pumping there is no more water to flow over the weir. How can your drain keep getting water to drain? Is your overflow box large and it just keeps draining the water from that? That can't be that much water, how big is the overflow box or drain box? Internal or external?

 

[liz62]

I don't know - I am just telling you that this is what happened when I turned the power off.

I agree with everything that you said - maybe I just have to much water in my sump and it looked like it was going to overflow and was coincidental that I pulled the drain lines out of the water at the same time that it looked like it was going to overflow??

 

[liz62]

I will set it up again (and lower my water level in the sump) and then turn everything off to see if it happens again.

 

[TheFishMan65]

How about a picture. It sounds like the overflow box is to large.

 

[CJBROWN]

I will set it up again (and lower my water level in the sump) and then turn everything off to see if it happens again.

How 'bout a photo or two?

Perhaps your return line from your pump is draining back. They will do that you know. If you have it plumbed through a bulkhead into the tank it will drain back until the water level reaches the level of the bulkhead and return lines.

For this reason I went over the top with my return line, and drilled an anti-siphon hole in it right at the water line. When the pump shuts down it will siphon back 'till the hole lets air in and breaks the siphon.

If your return lines are 3" below the waterline of the tank it will keep draining back 'till it reaches the level of the return line. If it's all under water it will siphon 'till it reaches the bottom of your return outlets.

A check valve in your return may make sense depending on your configuration. They are known to fail though, and they restrict flow. That's why other means for preventing back flow are employed. Some put the return outlets above the waterline so they can't siphon back.