Herbie on dual overflow

[vbsaltydog]

You're welcome.

 

[cubsfan16]

I'm looking to do the same thing. Did this work for you? I was concerned with the open emergency overflow becoming stagnate but also want to avoid the over the over the side return.

 

[vbsaltydog]

Yes, it works. If you are concerned about the overflow(s) becoming stagnant, you can always drop a small powerhead in the overflow chamber(s). A MJ400 would work to keep the overflows gently churning.

 

[cubsfan16]

Just curious, is your overflow silent with this configuration and are you having stagnation issues? I have a 120 AGA which has small circulation vents in the overflow that I hope will minimize stagnation but have some MJ1200's laying around I can use if necessary. Does your emergency drain maintain the depth (so small trickle down that drain?) Did you oversize the diameter of your drain line(s)? Sorry, I know there are ton's of threads on this but have yet to find someone that is running the same setup I plan to use.

 

[vbsaltydog]

Just curious, is your overflow silent with this configuration and are you having stagnation issues?

Yes, it is silent. There is no more stagnation than there would be with a durso or any other standpipe. If you set any standpipe high then the water in the bottom of the overflow doesn't move much. If you set the standpipe low then you avoid the deep water stagnation but you have a noisy waterfall effect. So the answer is to drop a cheap, low flow powerhead into the deep overflow.

I have a 120 AGA which has small circulation vents in the overflow that I hope will minimize stagnation but have some MJ1200's laying around I can use if necessary.

MJ1200s would work but I would recommend MJ400s

Does your emergency drain maintain the depth (so small trickle down that drain?)

The ball valve on the siphon drain is how you set the water level so that there is only a trickle down the open drain. You choke it so that the siphon drain is pulling slightly less than the return pump returns, forcing the excess into the open drain.

If you are returning 500 gph, you choke the siphon drain so that it pulls 450 gph, leaving 50 gph to flow down the open drain. Thats just an example but you get the idea.

Did you oversize the diameter of your drain line(s)?.

No, theres no reason to. My tank is drilled for 1" drains/returns.

A 1" drain at full siphon can pull a lot of water.

The returns reduce to 3/4" at the loc line and my return pump's outlet is 3/4" so my return lines are 3/4". There would be no benefit to enlarging my return plumbing, plus my return pump is pressure rated.

 

[perverseosmosis]

I'm looking to do the same thing. Did this work for you? I was concerned with the open emergency overflow becoming stagnate but also want to avoid the over the over the side return.

I've got it all plumbed up but I haven't filled the tank up completely. I have it in my garage while I finish it up and it's not exactly level yet. Once I shim it up (hopefully this weekend) I'll fill it up and report back.

I've filled each overflow up independently and things seem to work as expected.

 

[vbsaltydog]

Great. Report back after you get it running.

 

[cubsfan16]

Following your progress....going to go pick up some PVC , fittings and baffles for my sump today. So I'm not far behind you.

 

[perverseosmosis]

So things do equalize across compartments. Would this work then?


[o O] [O o]
.1.2...3.4


1) Return pump
2) Open drain
3) Syphon
4) Return pump

It's Herbiean in that there's only 2 drains. If I understand you correctly, the level in the overflows is established by the height of 2.

I suppose a BeanAnimal approach would swap 1 with an emergency drain.

That should be fine and yes, (2) sets the water level.
IMO bean animal's approach is overkill.

I leveled my tank and filled it up. What's described here isn't my experience

My experience is exactly what I posted here:

It makes sense to me that, in a closed system, wherever there is an open drain, there will be a constant water level. I guess what I'm not understanding (yet, and thanks for helping me get there) is this:

1) If a compartment doesn't have an open drain, but instead a syphon, what's maintaining a constant water level? Does an open drain in one compartment affect the water level of a separate overflow compartment? Even if they're not "connected"? Is this the magic of Herbie physics ?

2) If a compartment does have an open drain, what keeps it from taking on so much water that it gurgles? The return volume is going to be split evenly across both overflow compartments. It seems like I'd have to limit the total return volume to only twice that trickle.

One overflow compartment is just drain volume matched to a pump and the other compartment is a durso, which gurgles away as it consumes half the return flow.

The half-herbie in the one compartment (let's call it a durrrbie) will happily fill with water until its level matches that of the display tank.

So far this is a bust

 

[vbsaltydog]

If your siphon is choked so that it drains slightly less than the return flow rate and your siphon is maintained then how are you flooding the open drain chamber? Where is the water coming from that is flooding the open drain chamber?

500 gph siphon
550 gph return
50 gph positive to the dt water level, divided by two because equalization will spread it evenly across the entire dt surface area, adding 25 gph to each overflow but because the siphon is already maxed out, the siphon chamber level should be level with the dt and the full 50 gph excess should be easily handled by the open drain chamber.

If your open drain is flooding then you are returning much faster than you are draining. Open your siphon more and if it still does it with the siphon fully open, put a valve on your return line and choke it off.

Depending on the amount being processed, minor adjustments in the siphon draw could make all the difference.

 

[perverseosmosis]

My siphon is choked to match the rate of water coming over that overflow as closely as possible. However, it's not perfect and over an hour or so, the level is either too low (and the siphon breaks) or too high (and the water rises over the top of the overflow).

My open drain isn't flooded, it's just taking more water than it can do so silently.

In a traditional herbie with one open drain and one syphon, the open drain is there for two reasons:

1) If the syphon rate is 10% variable, you error by choking the syphon and send at most 10% down the open drain.
2) If the syphon closes up for some reason, you've got an emergency path for the water.

However, because the open drain and syphon aren't in the same compartment, my open drain isn't taking 10% of the flow, which can comfortably cruise down the sides of the drain. Mine is taking 50% and it sounds like your average durso, because it is.

I've played with this in two other ways:

1) I ran a water-filled tube between the two overflow compartments (making them at least part of the same system. This stabilized the level of the water in the siphon compartment.

2) I ran the water in the siphon compartment all the way to the top, to the point where it really wasn't an overflow anymore . This does the same thing as running the tube between compartments. The tank becomes that tube.

Now that I understand this better, I think I'll probably run my return water over the back. Alternatively, I could fill it up with sand, as was suggested in another thread.

 

[perverseosmosis]

Actually, maybe I'll do this:


..A.....B
[o O] [O o]
.1.2...3.4


Compartment A:
1) Syphon
2) Open drain <---10% system-wide slop goes here

Compartment B:
3) Syphon
4) Return pump

To keep both compartments within the same system, I'll either run compartment B to the point of flooding over the top, or connect them with a tube.

 

[BSmitty22]

Actually, maybe I'll do this:


..A.....B
[o O] [O o]
.1.2...3.4


Compartment A:
1) Syphon
2) Open drain <---10% system-wide slop goes here

Compartment B:
3) Syphon
4) Return pump

To keep both compartments within the same system, I'll either run compartment B to the point of flooding over the top, or connect them with a tube.

I think that setup will work the best. as long as your open/emergency drain is the larger one

 

[perverseosmosis]

Yay. This works great. Just drops going over the open drain makes the whole thing silent.

I ended up not connecting the two compartments. The level in compartment B floats around a bit, but that's easily compensated for by running it high.

On to something else! Thanks for your help everyone!

 

[vbsaltydog]

The bouncing level in compartment B is from fluctuations in return pump output. There is no way to avoid that. Glad you got it running.

I am testing another method and will update the thread when the results are in.

 

[cubsfan16]

So what exactly did you end up doing? Running return over back?

 

[perverseosmosis]

So what exactly did you end up doing? Running return over back?

No, I was able to avoid that.

Crummy ASCII art of the situation:

o = 3/4"
O = 1"

..A.....B
[o O] [O o]
.1.2...3.4


Compartment A:
1) Syphon + gate valve (level set an inch or so below open drain in slot 2)
2) Open drain <---10% system-wide slop goes here

Compartment B:
3) Syphon + gate valve (level set at whatever)
4) Return pump (out to display)

Water has one way into the tank and three ways out. The water level in compartment A is tied to the level of the open drain.

The water level in compartment B floats. The only way I've found to prevent that is to
1) let the water run all the way to the top (so any extra has to go down the open drain in the other compartment).
2) Connect the two compartments with a water filled tube.

While it's kinda neat to watch the direction of the water change in the tube as the dynamics of the system change, my feeling is that it will ultimately fill with air and stop connecting the two chambers.

I'll probably just run the B compartment completely full and chuck a power head back there for circulation.

 

[cubsfan16]

Ah, didn't see the illustration on my iPhone. So silent as described even with the compartment B fluctuation? (ie no gurgle/loss of siphon when water level drops without tube)

 

[perverseosmosis]

Ah, didn't see the illustration on my iPhone. So silent as described even with the compartment B fluctuation? (ie no gurgle/loss of siphon when water level drops without tube)

If the level in B dropped to the point where the siphon broke, I think you'd hear significant gurgling. My plan is to choke off the siphon in B to the point where the overflow doesn't typically consume all the water thrown at it. It fills up and the remainder goes down the open drain in A.

I'll check back in later and let you know if it's turned into a disaster

 

[vbsaltydog]

You should be fine UNLESS both of your siphons get blocked, in which case, your single open drain will likely be insufficient to handle the drainage needed and you will have a flood as the tank overflows.

The way around this is to ensure that your open drain, at full siphon, can handle the volume of your twin choked siphons OR close off your Compartment B siphon completely, it really isn't doing much for you in your current configuration.