Silent and Failsafe Overflow System - Page 386

Sisterlimonpot · 03/31/2018, 12:10 PM

Years ago i read that article and I used the your return setup with great success on a 75 gal. however I have read many different variations to your design coupled with either a weir or coast to coast drain. there were pros and cons of each but I don't remember... In a month or so I will be turning my attention to plumbing my 300 and I want to be as current with the information as possible without combing through tons and tons of posts.

It makes sense that it's under construction, because I went to your website last night and noticed there were a lot of supporting pictures missing....

sub2hour · 04/04/2018, 08:24 AM

Does anyone know if it's worth upsizing the drain pipes after a 1" bulkhead to 1 1/4 and likewise in the overflow box on all 3 lines? I know the Durso utilizes the upsizing for the open channel pipe. Obviously it would be easier to not upsize because of all of the reducer bushings/adapters required to change the size. Also is a gate valve really useful on the siphon line or is a ball valve adequate? [IMG]

[/IMG]
Thanks!

PC_LOAD_LTR · 04/04/2018, 08:28 AM

There really isn’t a need to increase the pipe size beyond that of the bulkhead. Much easier to stay consistent. I am actually replacing a durso with a bean and have a 1-1/4 bulkhead that i am reducing to 1”

Ball valves should only be used for on/off. It would be very difficult to balance the flow without a gate valves adjustability

Sent from my iPhone using Tapatalk

Lsufan · 04/05/2018, 09:19 PM

Upsizing the pipe is a good idea at times but it definitely isn’t a rule eighther. I definitely wouldn’t downsize the pipe. Need to know more about your system to say if it would be worth it or not. The biggest thing u gain by upsizing the pipe is the open channel can handle more flow & remain silent. It would also be able to handle more flunctuation in the system & remain silent without having to tune the valve.

So it isn’t as much about overall flow in most cases. A 1” syphon can handle the majority of people’s systems. The larger the open channel the more water it can take & remain silent. For example, say u run a reactor or manifold off your return pump. If u have a 1” plumbing & u turn the reactor off, u will more then likely have to adjust the valve for it to remain silent. If u have 1.5” plumbing u could turn off the reactor or whatever it’s feeding & the system remain quiet because the 1.5” open channel can handle the flunctuation.

A gate valve makes it easier to fine tune the system but I wouldn’t say they are a must. I have had no issues using ball valves in the past & I still use a ball valve on one of my setups. I like to have as long of a overflow box as possible, so a ball valve works fine. The newer ghost type overflows that have become popular can have more issues using a ball valve because the exterior boxes are small. It’s really just the 12” & maybe 16” boxes because they hold so little water. Once u get to the larger versions it shouldn’t be a issue. Not all ball valves are created equal. The really cheap ones would have more issues then a higher quality double Union ball valve for instance.

BeanAnimal · 04/08/2018, 02:51 PM

I think gate valves are a waste of money... I have never had an issue dialing the system in with a ball valve. That said, in 10 years I can count on one hand the number of times I have had to adjust the system.

Bean

arju · 04/10/2018, 09:53 AM

bottom drill tank able to apply beananimal?

DougSupreme · 04/10/2018, 01:35 PM

Quote:

Originally Posted by BeanAnimal

Teeth greatly impede surface skimming. That said, it really depends on the livestock, linear overflow length and flowrate. Small overflow with high flow will tend to allow too many fish to take the trip to the sump. Teeth help to prevent that, but (again) severely limit the surface skimming. The answer? A longer overflow, of course.

So, if I was to have a 48" external overflow, would teeth cause too much of an issue? Probably only running 1500gph over the edge.

Floyd R Turbo · 04/10/2018, 01:57 PM

a 48" notched weir with 1/4" wide notches that are 1/2" apart (1/4" teeth) would have about 93 notches, at a depth of 1" per notch that should flow over 3500 GPH so I would sa you're fine, from a flow perspective. Make the notches 1.25" deep and you're over 5000 GPH, if you then factor in the teeth clogging over time, even 50% clogging and you're well over 1500 GPH.

For comparison, the same weir at 48" with no notches only needs 0.25" of water over the top of it to achieve 1500 GPH.

DougSupreme · 04/10/2018, 02:24 PM

OK, so here's the plan (tentatively)

I'm going to build a 48x36x24 tank with an external coast to coast overflow. I'm thinking it might be more structurally sound to extend the side panels (36" panels) an extra 5-6" and make the back panel shorter than the front. Then I would attach the back and bottom of the over flow to the side pieces creating a true coast to coast overflow.

I plan on using your 3 pipe silent standpipe setup. I will drill an additional hole in the overflow bottom to run my return line, and may potentially include 4 holes in the back panel for a closed loop.

My main question is, how much shorter should I make the back panel if I want it to be able to handle 1500-2000 gph silently?

Also, is there a benefit of extending the side panels to help create the overflow box? My thought process is that the overflow box would be more than just siliconed to the back, therefore it would be less likely to leak/fall off

Floyd R Turbo · 04/10/2018, 02:53 PM

Depends on many factors I suppose. There's many ways to do it. But pics and/or a sketch help. I can't envision what you're describing, either that, or brain is in the wrong gear

DougSupreme · 04/10/2018, 06:35 PM

delete

DougSupreme · 04/10/2018, 06:39 PM

Quick and dirty. This is a side view of the tank. Will the larger side panels make the external overflow stronger? (Less likely to come loose and leak)

Just a thought I had, wondering if it will work

Sent from my SM-G930V using Tapatalk

Lsufan · 04/10/2018, 08:17 PM

I would just make the overflow box separate from the tank & attach it to the back of the tank. On a box that size I would support it with some triangle pieces under the overflow box.

As far as the notch in the back glass, it depends where u want the water level. I would be comfortable with it being 1.5”. Any more then that & the water level would look low inside of the tank. Any less then that & u start cutting it pretty close once u get wavemakers going on inside of the tank.

How are u wanting to attach the teeth. On a box that size teeth won’t cause issues as far as flow. What it does is cut the surface skimming pretty much in half. I think teeth would be more hassle then it’s worth, which to me they aren’t worth much anyways because I prefer a smooth weir

Floyd R Turbo · 04/11/2018, 08:20 AM

What confused me was the description of "extending the sides". I now caught that you are building the tank (or having it custom built). Out of glass or acrylic?

DougSupreme · 04/11/2018, 08:28 AM

Quote:

Originally Posted by Floyd R Turbo

What confused me was the description of "extending the sides". I now caught that you are building the tank (or having it custom built). Out of glass or acrylic?

Building it myself out of glass. Did you think 3/16" is sufficient?

Jk. Building it out of 3/8" possibly 1/4" for the overflow

Sent from my SM-G930V using Tapatalk

Floyd R Turbo · 04/11/2018, 08:41 AM

I'm an acrylic guy so I can't answer that heh heh

What I can say is that if you build with the sides on top, that's opposite of the normal technique (for both acrylic and glass) where the front and back panels are on top of the end panels (the edges of the ends are bonded to the inside face of the front/back panel) so "extending the sides" becomes a constructability change, and you may not want to go there. If anything, on the front of your tank, you're going to see the end of the side panels, which is kinda ugly.

My personal advice would be to drill the back panel for pass-through holes and then use a very thin inside coast-to-coast and an outside box made of either glass or acrylic, and make those separate pieces. Basically either buy or make your own version of a Shadow or Ghost.

The reason I say this is because it allows for a lot of flexibility and allow you to correct something if you later realize that it doesn't work exactly the way you want it or envisioned it, or if you want to do something a bit different, etc. Making is part of the structure of the tank sounds great on paper but it also locks you into a solution and limits your ability to change.

Making a sturdy acrylic box and using bulkheads to hold it in place is a solid long-term solution. If you want some peace of mind, you can add in some kind of support method to take stress off the box and mitigate against any potential failure points (like weight of hanging off the back panel, if you're worried about that)

Cutting a notch in the top of the back panel or cutting teeth in the glass creates a huge amount of failure points. Lowering the height of the back panel relative to the sides would probably work, then add in a notched attachment or gutter guard etc, there's more than one way to do it, but I go back to the idea of building an overflow solution into the tank as having it's drawbacks...because I've done it.

Lsufan · 04/11/2018, 06:30 PM

Im the one that called it a notch & probably shouldn’t have. It sounds to me he is planning on just making the back pane of glass shorter then the front & sides.

I’m no builder & they have calculators for glass thickness if u know how to use them. Imo 3/16 would be way undersized. The only way I see 1/4” being ok is if u use trim & have a center brace & it’s still probably to small. If u plan on it being rimless then I would think it would have to be atleast 1/2”. I don’t think 3/8” would even be enough. I’m not positive on that so u definitely want to find out before getting glass.

DougSupreme · 04/11/2018, 06:36 PM

Quote:

Originally Posted by Lsufan

Im the one that called it a notch & probably shouldn’t have. It sounds to me he is planning on just making the back pane of glass shorter then the front & sides.

I’m no builder & they have calculators for glass thickness if u know how to use them. Imo 3/16 would be way undersized. The only way I see 1/4” being ok is if u use trim & have a center brace & it’s still probably to small. If u plan on it being rimless then I would think it would have to be atleast 1/2”. I don’t think 3/8” would even be enough. I’m not positive on that so u definitely want to find out before getting glass.

I'm building the tank out of 3/8". I'm considering building the overflow out of 1/4" but I May go larger if the price isn't much

Sent from my SM-G930V using Tapatalk

SumptyDumpty · 04/13/2018, 07:57 PM

Here is a channel that had a modified Bean Animal I saved to my bookmarks as well as a video that he just added today!

Type in the title of the video on youtube or watch the linked video, your choice.

Justin Stanley
Published on Apr 13, 2018
Overflow Spotlight and Setup
https://www.youtube.com/watch?v=NZ9ROj24L-4

Older video from him.
Justin Stanley
Published on Mar 25, 2015
Modified "Bean Animal" Overflow Drain Test
https://www.youtube.com/watch?v=oya6X3aLUOo

Chad_P · 04/15/2018, 04:35 PM

Dumb question but when I hold my finger over the RO/DI line (connected to quick connect fitting) I don’t get a quick flush from the open channel. Any idea what may cause this? I have my siphon channel lower than the open channel. Can’t post a good pic because overflow is against wall.

Sent from my iPhone using Tapatalk

Lsufan · 04/15/2018, 08:30 PM

Because it still has to purge the air from the pipe. So it would have to build up enough to purge the air. In order to test it out u would need to close the valve on the syphon like it got clogged. That way the water builds up in the overflow box enough to purge the air from the open channel

Chad_P · 04/15/2018, 08:32 PM

Ah that makes sense. Thought I had something wrong but was confused because it was running so quiet. Thank you for clarifying!

Sent from my iPhone using Tapatalk Pro

DougSupreme · 04/17/2018, 11:54 AM

Quote:

Originally Posted by DougSupreme

I'm building the tank out of 3/8". I'm considering building the overflow out of 1/4" but I May go larger if the price isn't much

Sent from my SM-G930V using Tapatalk

So, the plans have changed. I'm still planning on building the tank in the same configuration, but instead of glass, I've decided to use plywood. I'm 100% confident in my ability to make it work and look good.

I had too many people show concern with with building my first glass tank that large (wife was the deal breaker)

Still going to use a coast to coast overflow with the Bean animal drain setup.

Wish me luck. I'll probably start a build thread soon

Sent from my SM-G930V using Tapatalk

Chad_P · 04/19/2018, 03:27 PM

quick question here related to stopping/starting the return pump. Seems I have trouble getting the siphon going. When it's recommended to have the drain into the sump no deeper than 1/2" below the water level, is that when the system is running or when the return pump is off and the return line has siphoned down a bunch of water back into the sump?

DougSupreme · 04/19/2018, 04:05 PM

Quote:

Originally Posted by Chad_P

quick question here related to stopping/starting the return pump. Seems I have trouble getting the siphon going. When it's recommended to have the drain into the sump no deeper than 1/2" below the water level, is that when the system is running or when the return pump is off and the return line has siphoned down a bunch of water back into the sump?

I believe it's when it's running. You can drill a couple of small holes just above to running water line to help purge the air from the siphon line

Sent from my SM-G930V using Tapatalk

03/31/2018, 12:10 PM	#9626
Sisterlimonpot R.C. Fraternity President Join Date: Dec 2008 Location: Litchfeild Park AZ Posts: 11,490 Blog Entries: 2	Years ago i read that article and I used the your return setup with great success on a 75 gal. however I have read many different variations to your design coupled with either a weir or coast to coast drain. there were pros and cons of each but I don't remember... In a month or so I will be turning my attention to plumbing my 300 and I want to be as current with the information as possible without combing through tons and tons of posts. It makes sense that it's under construction, because I went to your website last night and noticed there were a lot of supporting pictures missing.... __________________ Jimmy MASVC President Dishes are done man! Current Tank Info: 300 in progress Last edited by Sisterlimonpot; 03/31/2018 at 12:22 PM.

04/04/2018, 08:24 AM	#9627
sub2hour Registered Member Join Date: Oct 2002 Location: St. Louis Posts: 8	Upsizing the Bean Animal Pipes from the bulkhead size Does anyone know if it's worth upsizing the drain pipes after a 1" bulkhead to 1 1/4 and likewise in the overflow box on all 3 lines? I know the Durso utilizes the upsizing for the open channel pipe. Obviously it would be easier to not upsize because of all of the reducer bushings/adapters required to change the size. Also is a gate valve really useful on the siphon line or is a ball valve adequate? [IMG][/IMG] Thanks!

04/05/2018, 09:19 PM	#9629
Lsufan Registered Member Join Date: Nov 2013 Location: Baton Rouge Posts: 1,410	Upsizing the pipe is a good idea at times but it definitely isn’t a rule eighther. I definitely wouldn’t downsize the pipe. Need to know more about your system to say if it would be worth it or not. The biggest thing u gain by upsizing the pipe is the open channel can handle more flow & remain silent. It would also be able to handle more flunctuation in the system & remain silent without having to tune the valve. So it isn’t as much about overall flow in most cases. A 1” syphon can handle the majority of people’s systems. The larger the open channel the more water it can take & remain silent. For example, say u run a reactor or manifold off your return pump. If u have a 1” plumbing & u turn the reactor off, u will more then likely have to adjust the valve for it to remain silent. If u have 1.5” plumbing u could turn off the reactor or whatever it’s feeding & the system remain quiet because the 1.5” open channel can handle the flunctuation. A gate valve makes it easier to fine tune the system but I wouldn’t say they are a must. I have had no issues using ball valves in the past & I still use a ball valve on one of my setups. I like to have as long of a overflow box as possible, so a ball valve works fine. The newer ghost type overflows that have become popular can have more issues using a ball valve because the exterior boxes are small. It’s really just the 12” & maybe 16” boxes because they hold so little water. Once u get to the larger versions it shouldn’t be a issue. Not all ball valves are created equal. The really cheap ones would have more issues then a higher quality double Union ball valve for instance. Last edited by Lsufan; 04/08/2018 at 11:12 PM.

04/10/2018, 01:57 PM	#9633
Floyd R Turbo Either busy or sleeping Join Date: Oct 2009 Location: West Des Moines, IA Posts: 4,265 Blog Entries: 15	a 48" notched weir with 1/4" wide notches that are 1/2" apart (1/4" teeth) would have about 93 notches, at a depth of 1" per notch that should flow over 3500 GPH so I would sa you're fine, from a flow perspective. Make the notches 1.25" deep and you're over 5000 GPH, if you then factor in the teeth clogging over time, even 50% clogging and you're well over 1500 GPH. For comparison, the same weir at 48" with no notches only needs 0.25" of water over the top of it to achieve 1500 GPH. __________________ Algae Scrubber Basics!!! GOOGLE "algaescrubber zoho" General Interest Forums --> Advanced Topics --> Algae Scrubber Basics (sticky) --> POSTS #3251-64 (Basics), #5206 (Cleaning), #6884 (LEDs), #729

04/10/2018, 02:24 PM	#9634
DougSupreme Registered Member Join Date: Oct 2003 Location: Illinois Posts: 1,226	OK, so here's the plan (tentatively) I'm going to build a 48x36x24 tank with an external coast to coast overflow. I'm thinking it might be more structurally sound to extend the side panels (36" panels) an extra 5-6" and make the back panel shorter than the front. Then I would attach the back and bottom of the over flow to the side pieces creating a true coast to coast overflow. I plan on using your 3 pipe silent standpipe setup. I will drill an additional hole in the overflow bottom to run my return line, and may potentially include 4 holes in the back panel for a closed loop. My main question is, how much shorter should I make the back panel if I want it to be able to handle 1500-2000 gph silently? Also, is there a benefit of extending the side panels to help create the overflow box? My thought process is that the overflow box would be more than just siliconed to the back, therefore it would be less likely to leak/fall off __________________ Intelligence is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad Current Tank Info: 75g mixed reef

04/04/2018, 08:28 AM	#9628
PC_LOAD_LTR Registered Member Join Date: Mar 2012 Location: Rochester, NY Posts: 68	There really isn’t a need to increase the pipe size beyond that of the bulkhead. Much easier to stay consistent. I am actually replacing a durso with a bean and have a 1-1/4 bulkhead that i am reducing to 1” Ball valves should only be used for on/off. It would be very difficult to balance the flow without a gate valves adjustability Sent from my iPhone using Tapatalk

04/08/2018, 02:51 PM	#9630
BeanAnimal Registered Member Join Date: Feb 2003 Location: Pittsburgh Posts: 20,772	I think gate valves are a waste of money... I have never had an issue dialing the system in with a ball valve. That said, in 10 years I can count on one hand the number of times I have had to adjust the system. Bean

04/10/2018, 09:53 AM	#9631
arju Registered Member Join Date: Dec 2017 Posts: 5	bottom drill tank able to apply beananimal?

04/10/2018, 02:53 PM	#9635
Floyd R Turbo Either busy or sleeping Join Date: Oct 2009 Location: West Des Moines, IA Posts: 4,265 Blog Entries: 15	Depends on many factors I suppose. There's many ways to do it. But pics and/or a sketch help. I can't envision what you're describing, either that, or brain is in the wrong gear __________________ Algae Scrubber Basics!!! GOOGLE "algaescrubber zoho" General Interest Forums --> Advanced Topics --> Algae Scrubber Basics (sticky) --> POSTS #3251-64 (Basics), #5206 (Cleaning), #6884 (LEDs), #729

04/10/2018, 06:35 PM	#9636
DougSupreme Registered Member Join Date: Oct 2003 Location: Illinois Posts: 1,226	delete __________________ Intelligence is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad Current Tank Info: 75g mixed reef

04/10/2018, 06:39 PM	#9637
DougSupreme Registered Member Join Date: Oct 2003 Location: Illinois Posts: 1,226	Quick and dirty. This is a side view of the tank. Will the larger side panels make the external overflow stronger? (Less likely to come loose and leak) Just a thought I had, wondering if it will work Sent from my SM-G930V using Tapatalk __________________ Intelligence is knowing that a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad Current Tank Info: 75g mixed reef

04/10/2018, 08:17 PM	#9638
Lsufan Registered Member Join Date: Nov 2013 Location: Baton Rouge Posts: 1,410	I would just make the overflow box separate from the tank & attach it to the back of the tank. On a box that size I would support it with some triangle pieces under the overflow box. As far as the notch in the back glass, it depends where u want the water level. I would be comfortable with it being 1.5”. Any more then that & the water level would look low inside of the tank. Any less then that & u start cutting it pretty close once u get wavemakers going on inside of the tank. How are u wanting to attach the teeth. On a box that size teeth won’t cause issues as far as flow. What it does is cut the surface skimming pretty much in half. I think teeth would be more hassle then it’s worth, which to me they aren’t worth much anyways because I prefer a smooth weir Last edited by Lsufan; 04/10/2018 at 08:23 PM.

04/11/2018, 08:20 AM	#9639
Floyd R Turbo Either busy or sleeping Join Date: Oct 2009 Location: West Des Moines, IA Posts: 4,265 Blog Entries: 15	What confused me was the description of "extending the sides". I now caught that you are building the tank (or having it custom built). Out of glass or acrylic? __________________ Algae Scrubber Basics!!! GOOGLE "algaescrubber zoho" General Interest Forums --> Advanced Topics --> Algae Scrubber Basics (sticky) --> POSTS #3251-64 (Basics), #5206 (Cleaning), #6884 (LEDs), #729

04/11/2018, 08:41 AM	#9641
Floyd R Turbo Either busy or sleeping Join Date: Oct 2009 Location: West Des Moines, IA Posts: 4,265 Blog Entries: 15	I'm an acrylic guy so I can't answer that heh heh What I can say is that if you build with the sides on top, that's opposite of the normal technique (for both acrylic and glass) where the front and back panels are on top of the end panels (the edges of the ends are bonded to the inside face of the front/back panel) so "extending the sides" becomes a constructability change, and you may not want to go there. If anything, on the front of your tank, you're going to see the end of the side panels, which is kinda ugly. My personal advice would be to drill the back panel for pass-through holes and then use a very thin inside coast-to-coast and an outside box made of either glass or acrylic, and make those separate pieces. Basically either buy or make your own version of a Shadow or Ghost. The reason I say this is because it allows for a lot of flexibility and allow you to correct something if you later realize that it doesn't work exactly the way you want it or envisioned it, or if you want to do something a bit different, etc. Making is part of the structure of the tank sounds great on paper but it also locks you into a solution and limits your ability to change. Making a sturdy acrylic box and using bulkheads to hold it in place is a solid long-term solution. If you want some peace of mind, you can add in some kind of support method to take stress off the box and mitigate against any potential failure points (like weight of hanging off the back panel, if you're worried about that) Cutting a notch in the top of the back panel or cutting teeth in the glass creates a huge amount of failure points. Lowering the height of the back panel relative to the sides would probably work, then add in a notched attachment or gutter guard etc, there's more than one way to do it, but I go back to the idea of building an overflow solution into the tank as having it's drawbacks...because I've done it. __________________ Algae Scrubber Basics!!! GOOGLE "algaescrubber zoho" General Interest Forums --> Advanced Topics --> Algae Scrubber Basics (sticky) --> POSTS #3251-64 (Basics), #5206 (Cleaning), #6884 (LEDs), #729

04/11/2018, 06:30 PM	#9642
Lsufan Registered Member Join Date: Nov 2013 Location: Baton Rouge Posts: 1,410	Im the one that called it a notch & probably shouldn’t have. It sounds to me he is planning on just making the back pane of glass shorter then the front & sides. I’m no builder & they have calculators for glass thickness if u know how to use them. Imo 3/16 would be way undersized. The only way I see 1/4” being ok is if u use trim & have a center brace & it’s still probably to small. If u plan on it being rimless then I would think it would have to be atleast 1/2”. I don’t think 3/8” would even be enough. I’m not positive on that so u definitely want to find out before getting glass.

04/13/2018, 07:57 PM	#9644
SumptyDumpty Registered Member Join Date: Jan 2016 Location: Royalton Posts: 105	Here is a channel that had a modified Bean Animal I saved to my bookmarks as well as a video that he just added today! Type in the title of the video on youtube or watch the linked video, your choice. Justin Stanley Published on Apr 13, 2018 Overflow Spotlight and Setup https://www.youtube.com/watch?v=NZ9ROj24L-4 Older video from him. Justin Stanley Published on Mar 25, 2015 Modified "Bean Animal" Overflow Drain Test https://www.youtube.com/watch?v=oya6X3aLUOo

04/15/2018, 04:35 PM	#9645
Chad_P Registered Member Join Date: Dec 2016 Posts: 208	Dumb question but when I hold my finger over the RO/DI line (connected to quick connect fitting) I don’t get a quick flush from the open channel. Any idea what may cause this? I have my siphon channel lower than the open channel. Can’t post a good pic because overflow is against wall. Sent from my iPhone using Tapatalk

04/15/2018, 08:30 PM	#9646
Lsufan Registered Member Join Date: Nov 2013 Location: Baton Rouge Posts: 1,410	Because it still has to purge the air from the pipe. So it would have to build up enough to purge the air. In order to test it out u would need to close the valve on the syphon like it got clogged. That way the water builds up in the overflow box enough to purge the air from the open channel

04/15/2018, 08:32 PM	#9647
Chad_P Registered Member Join Date: Dec 2016 Posts: 208	Ah that makes sense. Thought I had something wrong but was confused because it was running so quiet. Thank you for clarifying! Sent from my iPhone using Tapatalk Pro

04/19/2018, 03:27 PM	#9649
Chad_P Registered Member Join Date: Dec 2016 Posts: 208	quick question here related to stopping/starting the return pump. Seems I have trouble getting the siphon going. When it's recommended to have the drain into the sump no deeper than 1/2" below the water level, is that when the system is running or when the return pump is off and the return line has siphoned down a bunch of water back into the sump?