Silent and Failsafe Overflow System
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PAreefer40
New member
Just to make sure I understand everything from all this reading, and before I drill: 1.5" BH's with 1.5" piping (all three lines and return line) will work perfectly fine on a 90g standard size setup? I have the BH's and drill for 1.5" but they seem HUGE. In the C2C setup, main siphon 1/4-1/2" from bottom of overflow, second line same distance from bottom but BH hole slightly above the main siphon (maybe like 1/4"?), and emergency drain same height as the secondary drain with upturned elbow. Distances drilled apart 1-1.5 times diameter (same from the top)? I only REALLY need a gate valve on the main siphon, correct? By the way, I'm only looking to do about 500GPH through my sump.
Thanks in advance,
Blair
Thanks in advance,
Blair
PAreefer40
New member
Because he said that's what he just happened to have laying around, so I figured I would make it all the same size instead of buying fittings to down size, but didn't realize how obnoxiously big 1.5" bulkheads are.
sleepydoc
Team RC
Yes, you have to realize that 1" PVC is actually 1.3" in diameter, and 1.5" pipe is actually 1.9" in diameter, then you need to add the thickness of the bulkheads and threads on top of that.
When drilling holes in your tank, you want them to be big enough for your needs, but oversizing can cause problems as well. Also, remember that resistance to flow is additive, so a 1" bulkhead followed by 1.25 or 1.5" pipe will flow more than a 1" bulkhead and 1" pipe. With a full siphon, even a 1" pipe will probably flow enough for your purposes, but you can up-size it to 1.25 or 1.5" after the siphon if you like. Keep in mind that larger gate valves are significantly more expensive as well. I have 1" bulkheads, 1.5" pipe and then downsized to a 1" gate valve to save a bit of money.
The size of the pipe does make a difference with the open channel drain. It is effectively a durso, and a 1.25" or 1.5" durso can quietly flow significantly more than a 1". You can still use the 1" bulkhead, but I'd recommend upsizing the pipe after the durso.
Many people also use a larger elbow in the overflow as well, just to keep the edge flow velocity lower at the intake and reduce the resistance.
PAreefer40
New member
Silent and Failsafe Overflow System
Ok. I'll have to return them then, last thing I need is problems when I start. But as far as what I said about spacing and setup, does that sound correct?
Ok. I'll have to return them then, last thing I need is problems when I start. But as far as what I said about spacing and setup, does that sound correct?
sleepydoc
Team RC
@ 500 gph, 1" will be plenty for your siphon.
Yes, you need a minimum of 1 hole diameter between edges, ideally 1.5 diameters. This will be much easier to do with 1" bulkheads.
1/2" is probably adequate between the bottom of the overflow and the elbow, but I would leave 3/4", just tl make cleaning easier.
You should be able to drill all 3 holes at the same height. If the open channel is a bit higher it shouldn't matter. Make sure top of the emergency drain is a bit below the lip of the frame or top of the tank so the tank doesn't overflow when it kicks in. I'd probably allow about 3/4"; that's just a guess, though.
jwccwj
New member
Just planning ahead here guys as I don't have a tank yet but am keeping an eye out for a second hand 40 or 50g. For a smaller tank of this size would three 1" bulkheads with 1" plumbing on the full siphon and emergency and 1.25"or 1.5" piping on the open channel be acceptable? I will have a below tank sump in the stand and most of my flow will be using power heads so I'm guessing at 10x turnover I'll be pushing about 500gph.
Thanks.
Thanks.
jwccwj
New member
chatyak
New member
Could someone shed some light for me please on why BRS setup the bean animal system in this way. Have I missed something?
https://youtu.be/q1tAnhIGpgA?t=16m24s
Video should be loaded to right timing.
The full siphon and open channel are the same height in the original design yes? With the airline tubing supposed to be higher than the emergency standpipe.
In this video - they have it where the emergency is highest, open channel is 2nd highest w/drilled hole.. and full siphon is lowest.
https://youtu.be/q1tAnhIGpgA?t=16m24s
Video should be loaded to right timing.
The full siphon and open channel are the same height in the original design yes? With the airline tubing supposed to be higher than the emergency standpipe.
In this video - they have it where the emergency is highest, open channel is 2nd highest w/drilled hole.. and full siphon is lowest.
jason2459
Well-known member
Way earlier in this thread its suggested to do that. Or at least mentioned that it can be setup that way.
That is how I have mine setup. The emergency is under the height of the lip of the tank and open is slightly lower then the emergency. The emergency is always dry and open channel always has a very small amount of flow in it. On start up just before the full siphon is hit the open channel gets more flow to it and the emergency almost is hit. Not even a mm more and it would break over the top of it. Once the siphon kicks in the level goes down to the open.
That is how I have mine setup. The emergency is under the height of the lip of the tank and open is slightly lower then the emergency. The emergency is always dry and open channel always has a very small amount of flow in it. On start up just before the full siphon is hit the open channel gets more flow to it and the emergency almost is hit. Not even a mm more and it would break over the top of it. Once the siphon kicks in the level goes down to the open.
chatyak
New member
Ahhh - thank you. I'll try to find where in the thread this trend started. Do you know why it was moved from the original?
I do like it - seems easier in the video setup.
sleepydoc
Team RC
Yes - bean's original setup was with a coast to coast and had the siphon and open channels at the same height. An external overflow box allows for some changes in the configuration.
The siphon can be anywhere at or below the open channel level. (I suppose it could be above, but you may encounter difficulties starting up, and there's no reason I can think of to do so.) There is no reason it can't be 12" below the open channel if your overflow allows; it just needs to stay submerged and maintain a full siphon.
The open channel is at or above the siphon level. As Jason said above, on startup the water level rises significantly higher and approaches the level of the emergency. The typical startup sequence is:
A couple of other details to note:
If the air intake for the open channel gets occluded, it converts to an unrestricted siphon with no gate valve and will rapidly drain the overflow box until it entrains enough air to break the siphon. If the open channel and siphon are at the same level, the siphon will also entrain air. The water level will increase and the system will never start up properly. This is part of the reason the air line is placed above the level of the emergency drain in Bean's original design. Doing so keeps the water level stable at a higher level until air is purged from the siphon.
This placement also means that in case of failure and rising water levels, the order of backup operation is:
The setup that BRS uses has a potential flaw in that since the air intake for the open channel is a simple hole, it will occlude and convert to a siphon before the dry emergency kicks in. If the siphon is at a lower level than the open channel, the water may not drop enough to cause an issue and the siphon will still purge air as it should, but that depends on the flow and pipe characteristics. For their setup, the order of backup operation is:
The siphon can be anywhere at or below the open channel level. (I suppose it could be above, but you may encounter difficulties starting up, and there's no reason I can think of to do so.) There is no reason it can't be 12" below the open channel if your overflow allows; it just needs to stay submerged and maintain a full siphon.
The open channel is at or above the siphon level. As Jason said above, on startup the water level rises significantly higher and approaches the level of the emergency. The typical startup sequence is:
- Pump turns on. Water starts to flow and the water level in the overflow rises.
- As the water rises, the siphon channel initially has air in it, reducing the amount of water it can carry. As a result, the water level continues to rise above the normal operating level.
- The open channel carries the rest of the water. Air in the open channel also limits its capacity and the water level generally continues to rise (this depends on the total flow and the pipe capacities.)
- The water approaches the emergency drain level, or possibly goes over and stays at this level until the air is purged from the siphon.
- At this point the siphon capacity increases and drains the water out of the overflow down to its steady state level.
A couple of other details to note:
If the air intake for the open channel gets occluded, it converts to an unrestricted siphon with no gate valve and will rapidly drain the overflow box until it entrains enough air to break the siphon. If the open channel and siphon are at the same level, the siphon will also entrain air. The water level will increase and the system will never start up properly. This is part of the reason the air line is placed above the level of the emergency drain in Bean's original design. Doing so keeps the water level stable at a higher level until air is purged from the siphon.
This placement also means that in case of failure and rising water levels, the order of backup operation is:
- open channel takes more water
- dry emergency kicks in
- open channel airline tubing occludes and converts the open channel to a full siphon.
The setup that BRS uses has a potential flaw in that since the air intake for the open channel is a simple hole, it will occlude and convert to a siphon before the dry emergency kicks in. If the siphon is at a lower level than the open channel, the water may not drop enough to cause an issue and the siphon will still purge air as it should, but that depends on the flow and pipe characteristics. For their setup, the order of backup operation is:
- open channel takes more water
- open channel opening occludes and converts the open channel to a full siphon.
- dry emergency kicks in
chatyak
New member
Great post - thanks for that writeup. You lost me on the last list however. What is is about the BRS design that is bad?
"... in that since the air intake for the open channel is a simple hole, it will occlude and convert to a siphon before the dry emergency kicks in."
Is it bad to have the open channel kick in before the emergency?
Are you saying that having the main siphon and open channel at near height levels in the BRS case is iffy - only because the water fluctuations between open channel and main siphon will cause air getting into the main siphon (on startup, emergency) etc.?
Edit: Just re-read your post... It seems that the issue of having the open channel hole in the PVC between emergency and normal siphon is:
That it may allow the main siphon to get air in it and the water level will not remain stable. Yes?
Last edited:
jason2459
Well-known member
I think one of the pictures I posted previously was when I first setup my 180 and I didn't have the open channel airline installed. I just snapped this picture. Can see the mess of a patch job I had to do when I broke the back overflow rounding s corner and broke the glass. I was so not happy.
Closest is the open channel. The air line is slightly above the emergency. Hard to see but under all that saltcreep is a ziptie holding it in place.
Middle if course is the emergency and highest of the three.
Farthest is the full siphon and lowest of the 3. Then I also put some probes there. Also, on that far side is a failsafe switch. If by some crazy accident all the drains fail that switch will shutdown my return pump.
Edit: picture I mentioned
Edit edit. I guess you can't really even see the full siphon. It's by the probes. Ha!
Edit edit edit: I've been asked before and along the back of my canopy I've stapled regular patio screen. It's kept in many many many fish that have tried jumping over the years. I don't have anything over the water itself. I found fish getting hurt by eggcrate and trapped above the common 1/4" netting once they somehow jumped through. Now they can jump freely and slide back into the tank.
Closest is the open channel. The air line is slightly above the emergency. Hard to see but under all that saltcreep is a ziptie holding it in place.
Middle if course is the emergency and highest of the three.
Farthest is the full siphon and lowest of the 3. Then I also put some probes there. Also, on that far side is a failsafe switch. If by some crazy accident all the drains fail that switch will shutdown my return pump.
Edit: picture I mentioned
Edit edit. I guess you can't really even see the full siphon. It's by the probes. Ha!
Edit edit edit: I've been asked before and along the back of my canopy I've stapled regular patio screen. It's kept in many many many fish that have tried jumping over the years. I don't have anything over the water itself. I found fish getting hurt by eggcrate and trapped above the common 1/4" netting once they somehow jumped through. Now they can jump freely and slide back into the tank.
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sleepydoc
Team RC
The potential issue with the BRS setup is that at startup, the water level needs to stay high enough for the siphon channel to purge all of the air so it can reach its steady state flow. When the air inlet on the open channel pipe gets occluded, the open channel converts to a full siphon, dramatically increasing the flow and draining the overflow box. If that conversion and drop I level is enough to prevent the siphon channel from completely purging itself the system will just continue to oscillate and never reach a steady state.
As they have it designed, it may well work fine, because he open channel is set higher than the siphon channel, so if the air inlet on the open channel gets occluded and converts it to a full siphon, it may switch back to a lower-flowing open channel before the level gets low enough to disturbs the siphon channel, allowing it to continue to purge air.
As they have it designed, it may well work fine, because he open channel is set higher than the siphon channel, so if the air inlet on the open channel gets occluded and converts it to a full siphon, it may switch back to a lower-flowing open channel before the level gets low enough to disturbs the siphon channel, allowing it to continue to purge air.
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