Overflow Drain to fish room, down then up?

[coreytrv]

Have a tank going in the living room. Want to run the overflow lines from Display Tank to the Garage.

Attached is a scale diagram of the plumbing.

1 story house, drain will go from the display tank, into the crawlspace, then horizontally about 25' to the garage.
The overflow drain will need to go back up a few feet to the sump.

Any issues with drain going down, then back up? Relative distance between the overflow level and sump is about a 42"drop:

I assume Bean Animal is the best setup here.

Can gravity work here, or is a siphon setup needed, if siphon, I wonder if the 'up' portion of the line will have trouble purging air, of if there's enough head pressure to push through?

 

[KrisReef]

The drain line will always be filled with water but it will work fine.

 

[DCR]

The long horizontal run can become problematic, especially for the secondary emergency drains due to air getting trapped in it. I would make the piping oversized - at least 2" to allow the air to escape back upwards to the display tank. If the water flow is too much for the piping it will draw air into the horizontal air and if it cannot escape backwards, it will restrict the flow and cause instability. I would try to put a downward slope on the line through the crawl space if possible rather than running it flat. The full siphon should work but it may take a bit to get it started. I would put the full siphon valve on upleg at the end of the drain

 

[KrisReef]

The long horizontal run can become problematic, especially for the secondary emergency drains due to air getting trapped in it. I would make the piping oversized - at least 2" to allow the air to escape back upwards to the display tank. If the water flow is too much for the piping it will draw air into the horizontal air and if it cannot escape backwards, it will restrict the flow and cause instability. I would try to put a downward slope on the line through the crawl space if possible rather than running it flat. The full siphon should work but it may take a bit to get it started. I would put the full siphon valve on upleg at the end of the drain

I presumed that the horizontal drain pipe would be larger diameter, so my answer didn’t really answer the original question perhaps!

 

[coreytrv]

The long horizontal run can become problematic, especially for the secondary emergency drains due to air getting trapped in it. I would make the piping oversized - at least 2" to allow the air to escape back upwards to the display tank. If the water flow is too much for the piping it will draw air into the horizontal air and if it cannot escape backwards, it will restrict the flow and cause instability. I would try to put a downward slope on the line through the crawl space if possible rather than running it flat. The full siphon should work but it may take a bit to get it started. I would put the full siphon valve on upleg at the end of the drain

I'm thinking 2" piping on the overflow. Maybe Herbie style given the diameter of piping.

(2) x 2" pipes. I like the idea of the valve on the upleg. Then, I can tie in a fill valve to that line, close the siphon valve to flood the line, to help start the primary overflow siphon.

 

[Jimbo327]

As long as the top of the sump is lower than the overflow in the display....it will gravity drain just fine. No need for siphon. And not sure what the other posters are talking about air in the 2nd drain line.

Obviously, the bigger pipe size will help with drain rate.

 

[coreytrv]

As long as the top of the sump is lower than the overflow in the display....it will gravity drain just fine. No need for siphon. And not sure what the other posters are talking about air in the 2nd drain line.

Obviously, the bigger pipe size will help with drain rate.

I think they are talking about the initial purge of air from the line, which would result in a siphon.

Siphon's move a lot more water than a straight gravity drain which relies on slope. Almost all of our overflows, are designed to use siphon for efficiency, ie: Herbie, Bean Animal. The one that DOESN'T is a Durso, since the top has a hole in it to allow air to enter the pipe, and prevents a vacuum from forming.

To ensure the plumbing in this design doesn't result in air being trapped, and hindering performance, I should probably ensure there is a valve at the high point, which in this case is already the opening at the overflow in the DT. That leaves the elbow at the sump to be mindful of. With enough flow, this should purge automatically.

That means this drainage system should work due to the relative height different between the INLET and OUTLET.

We can verify flow rate by walking through hydraulic calculations as described on the Bean Animal site.
https://beananimal.com/articles/hydraulics-for-the-aquarist/
For those of you with remote fish rooms, this may be of interest. I use these calculations all the time to size return pumps to the plumbing in custom scenarios.

1. Calculate LD Ratios
2. Compute Cross-Sectional Area
3. Calculate Velocity
4. Determine Flow Rate
5. Account for Friction and Minor Losses
6. Adjusted Velocity
7. Adjusted Flow Rate
8. Convert Flow Rate to Gallons per Hour

Velocity is driven by gravity and the height difference. In this case 42" is relative HEIGHT difference between INLET and OUTLET, thus velocity = 4.58 m/s

Find LENGTH of entire plumbing run, including ALL fittings / valves. In this case, equivalent run is 75' = 22.86m

50' + 10% contingency + (8) sweep 90's (2.8 x 8 = 22.4) + (1) gate 1.4' = 73.8 = round to 75'

After following all calculations, accounting for head losses, friction, and fittings.

This system, using 2" pipe should achieve a flow rate of 2,254 GPH

Interestingly enough, if it didn't have to come up from the crawlspace that last 30" to get to the sump, the flow rate would be 2,952 GPH, that last bit of uphill is pretty costly in terms of GPH.

That means if I want 5x display volume running through the sump, I need to upsize to 2.5" piping, or use a Bean Animal, and plan on the secondary standpipe handling some of the flow the primary can't process.

 

[RocketEngineer]

Have a tank going in the living room. Want to run the overflow lines from Display Tank to the Garage.

Attached is a scale diagram of the plumbing.

1 story house, drain will go from the display tank, into the crawlspace, then horizontally about 25' to the garage.
The overflow drain will need to go back up a few feet to the sump.

Any issues with drain going down, then back up? Relative distance between the overflow level and sump is about a 42"drop:

I assume Bean Animal is the best setup here.

Can gravity work here, or is a siphon setup needed, if siphon, I wonder if the 'up' portion of the line will have trouble purging air, of if there's enough head pressure to push through?

What is the reason for the drain line going back up? Would it be possible to lower the sump or where the drains enter the sump to make it all downhill?

My concern would be a gradual buildup of detritus in the pipe at the corner. The long horizontal run would give time for particles to settle.

 

[Freenow54]

Have a tank going in the living room. Want to run the overflow lines from Display Tank to the Garage.

Attached is a scale diagram of the plumbing.

1 story house, drain will go from the display tank, into the crawlspace, then horizontally about 25' to the garage.
The overflow drain will need to go back up a few feet to the sump.

Any issues with drain going down, then back up? Relative distance between the overflow level and sump is about a 42"drop:

I assume Bean Animal is the best setup here.

Can gravity work here, or is a siphon setup needed, if siphon, I wonder if the 'up' portion of the line will have trouble purging air, of if there's enough head pressure to push through?

I would think you need slope. The line size would come into play as well. It would be no different than anything else in your home. Everything has a trap which is what you are creating. The setup should work but the things mentioned would effect flow rate and possible back up to my mind

 

[coreytrv]

What is the reason for the drain line going back up? Would it be possible to lower the sump or where the drains enter the sump to make it all downhill?

To place the sump on a table in the garage. But even if it was placed on the floor, it would still need to go back up at least a few feet to reach the top of the tank, otherwise it's not a 'free jet', it would be a submerged outlet in which the water pressure in the sump would slow down flow.

My concern would be a gradual buildup of detritus in the pipe at the corner. The long horizontal run would give time for particles to settle.

This is exactly the crux of the issue- some kind of filter, or cleanout that could be used to periodically remove buildup.

Perhaps can use that cleanout, and then open that to do a blowout periodically, ie: put a high pressure pump on the overflow inlet every so often, and scour the lines with pressure.

 

[coreytrv]

I would think you need slope. The line size would come into play as well. It would be no different than anything else in your home. Everything has a trap which is what you are creating. The setup should work but the things mentioned would effect flow rate and possible back up to my mind

Slope is not an essential component of a siphon, and has a negligible effect on flow...they typically only need 1-2%, and that is to keep air pockets from forming and getting trapped in the line. That should be negated by full siphon at the overflow, and high flow rates.

I do plan to slope a little bit though, there's enough room to get 1-2' per 100' of pipe.

@Freenow54, your point to maintain the areas that create air or detritus entrapment is key here.

 

[Freenow54]

Slope is not an essential component of a siphon, and has a negligible effect on flow...they typically only need 1-2%, and that is to keep air pockets from forming and getting trapped in the line. That should be negated by full siphon at the overflow, and high flow rates.

I do plan to slope a little bit though, there's enough room to get 1-2' per 100' of pipe.

@Freenow54, your point to maintain the areas that create air or detritus entrapment is key here.

Yes that is what I meant in reality it stops solids from building up and plugging the pipe

 

[DCR]

Just for clarification, I once built something similar to what you are proposing in a fish room with multiple tanks overflowing into a common 2" header that ran along the floor and then rose about 2 ft up to the top of the sump. These were straight open top overflows on each tank like a secondary drain (no full siphon). The system could not flow much water because air was being pulled down into the drains by the water overflowing down the pipe and could not pass back up against the water flow to escape. The problem was exaggerated becasue the drains came off the back of the tank relatively high up and I was probably trying to flow more water than what you would from a secondary drain, but it did not work until I added some vertical standpipes in the horizontal run along the floor to allow the air to escape. A liquid full pipe like a full siphon is completely different flow hydraulics from an open channel that is only partially flooded. That is why I am saying that the full siphon will probably be fine but the secondary and emergency overflows could become problems if there is too much water flow and not enough cross-sectional area for the air to escape.

 

[coreytrv]

Just for clarification, I once built something similar to what you are proposing in a fish room with multiple tanks overflowing into a common 2" header that ran along the floor and then rose about 2 ft up to the top of the sump. These were straight open top overflows on each tank like a secondary drain (no full siphon). The system could not flow much water because air was being pulled down into the drains by the water overflowing down the pipe and could not pass back up against the water flow to escape. The problem was exaggerated becasue the drains came off the back of the tank relatively high up and I was probably trying to flow more water than what you would from a secondary drain, but it did not work until I added some vertical standpipes in the horizontal run along the floor to allow the air to escape. A liquid full pipe like a full siphon is completely different flow hydraulics from an open channel that is only partially flooded. That is why I am saying that the full siphon will probably be fine but the secondary and emergency overflows could become problems if there is too much water flow and not enough cross-sectional area for the air to escape.

Thanks for sharing this...I think based on that, it would seem I need to upsize the primary siphon to 2-1/2".

That'll give me a flow rate of 3,522 GPH, which is what I'll engineer the system for. That means I won't need to rely on the open channel for nearly any flow.

Perhaps I can route the emergency drain to waste, using clear pipe, so that I can have visibility on it, and ensure it drains properly.

I just learned the original bean animal drain system uses an airline drilled into the secondary drain that is held at the weir's top water level...that way, if the system gets too high, it turns into a full siphon to help clear the water faster.

Courtesy of @BeanAnimal:
https://beananimal.com/projects/silent-and-fail-safe-aquarium-overflow-system/

 

[DCR]

That is an enormous amount of flow for a home aquarium. Think of filling a 5 gallon bucket in 5 seconds. The overflow weir should probably be at least 6ft long if not longer. I am not sure it is practical to move that much water over that type of distance without really large diameter piping if your full siphon fails. I don't know if you can count on your secondary or emergency going into full siphon mode with that up and down arrangement and the long horizontal run. I would definitely test it out to verify. I don't know the size of your tank but I doubt that you really need that much flow.

 

[BeanAnimal]

Interestingly enough, if it didn't have to come up from the crawlspace that last 30" to get to the sump, the flow rate would be 2,952 GPH, that last bit of uphill is pretty costly in terms of GPH.

That means if I want 5x display volume running through the sump, I need to upsize to 2.5" piping, or use a Bean Animal, and plan on the secondary standpipe handling some of the flow the primary can't process.

The "uphill" does not matter in a siphon. Ignoring friction and turbulence, the flow rate is determined by the difference in head height at of the pool being siphoned from and the pipe discharge if open ended, or the height of the pool if it is submerged.

In any case, the issue that you are going to have is air entrapment and sediment.

The secondary standpipe will be air locked due to the vertical section to the right. So again here, what goes in on the left will seek level on the right. If the pipe is large enough to prevent a siphon, the right hand discharge will act as a weir to the vertical pipe that feeds it (if that makes sense).

While this is all calculable at some level, there are a good bit of variables and you are not likely going to get the volume of flow that you wish.

To place the sump on a table in the garage. But even if it was placed on the floor, it would still need to go back up at least a few feet to reach the top of the tank, otherwise it's not a 'free jet', it would be a submerged outlet in which the water pressure in the sump would slow down flow.

As mentioned above, the "head" distance is the distance between the two connected pools of water, the submerged outlet does not cause additional "back pressure". Running the pipe back up, higher than the pool and letting discharge as a "free jet" just means less head distance and lower flow.

 

[Freenow54]

The "uphill" does not matter in a siphon. Ignoring friction and turbulence, the flow rate is determined by the difference in head height at of the pool being siphoned from and the pipe discharge if open ended, or the height of the pool if it is submerged.

In any case, the issue that you are going to have is air entrapment and sediment.

The secondary standpipe will be air locked due to the vertical section to the right. So again here, what goes in on the left will seek level on the right. If the pipe is large enough to prevent a siphon, the right hand discharge will act as a weir to the vertical pipe that feeds it (if that makes sense).

While this is all calculable at some level, there are a good bit of variables and you are not likely going to get the volume of flow that you wish.



As mentioned above, the "head" distance is the distance between the two connected pools of water, the submerged outlet does not cause additional "back pressure". Running the pipe back up, higher than the pool and letting discharge as a "free jet" just means less head distance and lower flow.

No insult intended but dont make this complicated. It is like I said it is just like the plumbing in your home the dip is the same as a P trap which prevents fumes from coming back from the sewer or septic bed also helps with vermin. There is no siphon involved in your home. Just proper sized pipe and slope

 

[coreytrv]

No insult intended but dont make this complicated. It is like I said it is just like the plumbing in your home the dip is the same as a P trap which prevents fumes from coming back from the sewer or septic bed also helps with vermin. There is no siphon involved in your home. Just proper sized pipe and slope

I appreciate the dialogue, it's helpful for teasing out these issues.

In aquariums, we use siphons because they are so much more efficient at moving large volumes of water: Herbie, Bean Animal are siphon designs, Durso is open channel.

A p-trap provides a place for water, and debris to deliberately settle in open channel drains. It works because the pipe is not pressurized. Rather home drainage is all based on gravity, they are vented and sloped (minimum 1/4" / ft.). Therefore a p-trap in a gravity system might allow a natural spot for heavier debris to settle, it won't stop the pipe from flowing. Just like when you use the sink, incoming water pushes p-trap water out of the trap, and takes its place.

Siphon drainage systems rely on pressurizing the pipe, no air, and move significantly more water. As a point of comparison, many of us rely on the following PVC flow charts for sizing pipe in our aquarium systems.

*Note in the chart below, 2" gravity to low pressure = 3300 gph
*If you compare this to a home plumbing system, Uniform Plumbing Code UPS Table 10.3.3 says 2" pipe is acceptable only for up to 24 FU = 1,260 gph, less than 1/2 of a pressure pipe.

All this being said, it does seem the 90 degree that goes from the low point, to vertical may present an entrapment issue for detritus. Which means:

Can I mitigate that by installing a cleanout, and periodically blowing the lines? Would this be a yearly, every 5 years type maintenance?

Or, do I need to put the sump on the floor of the garage.

**P.S. all of the 90's would be sweep 90's, if that makes a difference.

 

[BeanAnimal]

No insult intended but dont make this complicated. It is like I said it is just like the plumbing in your home the dip is the same as a P trap which prevents fumes from coming back from the sewer or septic bed also helps with vermin. There is no siphon involved in your home. Just proper sized pipe and slope

Not to be pedantic, but what is being described here is not a "P" trap due to the distances involved. The "P" trap works due to limitation of the "trap arm" length in relation to the "trap" and the "vent" that mathematically prevents it from being able to form a siphon.

The "24" and "30" numbers are not arbitrary, they are mathematical limitations (with a bit of safety margin) based in the pipe ID for 1.5" PVC plumbing to prevent the trap from siphoning and allowing sewer gas to rise into the fixture. Extend the trap arm, and/or the drop and the math changes and the trap siphons..... or air locks in some cases depending on downstream topology.


Your home plumbing is not a "siphon" because of the very carefully thought out vent requirements in ALL parts of the system from the sink and commode to the house trap and vent, to the open ended discharge into the city sewer. The system has nothing in common with what is being described above.

The aquarium system above could be designed for open channel gravity flow if both sides were properly vented and there was enough slope. The issue still becomes the discharge side with the discharge pool height being higher than the the lowest point of the plumbing. If this was your "home" it is where a lift or grinder pump would go.

So no insult, but this is not a "simple p trap".

 

[coreytrv]

That is an enormous amount of flow for a home aquarium. Think of filling a 5 gallon bucket in 5 seconds. The overflow weir should probably be at least 6ft long if not longer. I am not sure it is practical to move that much water over that type of distance without really large diameter piping if your full siphon fails. I don't know if you can count on your secondary or emergency going into full siphon mode with that up and down arrangement and the long horizontal run. I would definitely test it out to verify. I don't know the size of your tank but I doubt that you really need that much flow.

@DCR how much flow would you recommend?

I am engineering this system for 5x DT volume through sump. I can always tune it down, but would like to be able to strive for 5x.

est. 700 gallons x 5 = 3,500 GPH
Tank dimensions LxWxH 120 x 32 x 48
That means 1" of DT height = 16.62 gallons

3500 gallons / 16.62gallons / 60 minutes = 3.5 changes per minute

That means, I would be skimming the top 1" of tank water, approximately every 17 seconds.

Healthy flow, but isn't the standard 3x-5x through the sump? That's the tank's only filtration in this setup.