Overflow flow and noise reduction

[Gerryd]

Hey all,

I currently use a CPR overflow with dual 1" intakes. These feed into the trickle tower of my sump. I have gate valves on BOTH of the intakes just under the CPR overflow.

I am confused and am hoping that someone can set me straight in terms of flow and noise reduction. Here is my confusion.

These are 'facts' in my mind, but may not in fact be 'facts'

1. I understand from web research (I know) that a 1" diameter hose can flow approx 500-600 gph.

2. The CPR model I used is rated for 1200 gph. 2 x 1" intakes at max flow I assume is how they arrived at this value.

3. I have a mag 1800 gph driving the sump return.

4. Per the bean animal setup and other basic advice, folks say to do the following:

a. Use one siphon as full and be completely open.
b. Reduce the second siphon via the ball valve so it is NOT a full siphon.
c. Somehow magically, the FULL siphon will still flow the FULL AMOUNT OF BOTH INTAKES ???????

I am told that the full siphon should be quiet and the reduced siphon should be quiet as well. Okay, I get that and it is true.

My issue, however, is that when I CLOSE the second gate valve (not fully of course) to reduce the noise level, the FLOW to the sump and then back to the tank is MUCH REDUCED.

I am unsure how the flow for 2 1" intakes can be handled by a single 1" intake even if at full siphon. What am I missing here? This makes no sense to me whatsoever.

I can lower the noise level sure, but only at the cost of much reduced flow. I know I am missing something, but what is it???

I don't want to have a quiet tank but only flow 500-600 gph or so. That is not enough for a 220 gal tank or what I want to accomplish.

Appreciate any help.

[mike]

4. Per the bean animal setup and other basic advice, folks say to do the following:

a. Use one siphon as full and be completely open.
b. Reduce the second siphon via the ball valve so it is NOT a full siphon.
c. Somehow magically, the FULL siphon will still flow the FULL AMOUNT OF BOTH INTAKES ???????

Hi,

I believe your understanding of the bean animal overflow is reversed. The full syphon should be dialed back to handle about 90% of the return. There should be NO air line on this drain, which is why there is no noise. The secondary has an airline and is wide open, but only handles about 10% of the return.

Right now my tank (125G) is going through a dry start but it has a Bean Animal overflow with 1 inch pipes. From what I understand, a 1 inch drain, at full syphon, can handle about 2000 GPH. My sump has a Mag 1800 and a Mag 9.5, my total return is about 1500 GPH and it’s dead quiet, I had it running for about 2 weeks before I started my DSM. My full syphon drain has a gate valve on it and I have to dial it down a bit or it syphon’s too fast. My secondary drain is wide open and handles just the excess that may build up in the overflow. I also have an emergency pipe which technically should not be used. If you have any air going into your pipe you won’t get close to the full potential of the 1 inch pipe and it will be loud.

Regards,

Mike

[Tom Barr]

Mike is correct Gerry.

Think about it in terms of air and noise, which would suck more air into the over flow?
At say 90% flow, there is virtually no air coming into that drain.
And then say 10% drain..........is just a trickle..........not much noise nor much degassing.
If you run the pair at 50/50, then you get lots more noise and more degassing as air and water fight on the way down to the sump.

It's a fair simple modification for larger 2 drain type over flow systems.

[mike]

Gerry,

I would also like to add that it's important that all drains are submerged below water in the sump and the main full syphon also be below the waterline in your overflow. That way there is no air in the drain, which is what makes it quiet and able to drain almost 2000 gph

This also has the added benefit of much less co2 loss due to no splashing, which also means you don't have to completely seal your sump.

I'll be starting a build thred soon, unfortunately I won't have the overflow running until early September.


Mike

[Biollante]

Hi Gerry,

The point Mike makes may account for the flow volumes, remember that a submerged standpipe (sump end) will provide much greater flow (and be quieter) than release into air, technically to be a full siphon outflow must be submerged.

Bean Animal 1” stand pipes with 1½” bulkheads drilled through the back of the aquarium should be able to handle a little under 2000-gph (≈1960-gph calculated). Bean Animal 1” stand pipes drilled through the bottom should be able to run a bit over 2200-gph (≈2220-gph calculated). I have two systems running this configuration and measure just over 2000-gph actual. Each with all 3-standpipes terminating submerged in the sump.

At 1200-gph that is 7.7-^ft∕_sec, the Bean Animal should be able to handle that with ¾” pipe.

With a 1” pipe, I doubt 1200-gph will have much more than ½ to maybe ¾ open ball valve on the siphon (middle) standpipe.

One of the things I like is it does operate as advertised and any blockage or problem results in a lot of noise. It is been pretty much set and forget, the problem I had in the beginning was me being too aggressive, it takes a few minutes for things to “normalize.”

Learning to get not too excited at water change time was important for me.

Biollante

[Gerryd]

Hi all,

Thanks for all of the replies..

I will respond later with more detail, some pics, videos of my config.

For now, I will say this:

1. The sump design does submerge the end of the drains so they are not exposed to air.
2. The ribbed tubing does make a bit of noise and this can be replaced. It was what was available when I set it up
3. I would have to completely close one standpipe for the overflow to fill with water and submerge both stand pipes. I think I would have to mod this and that concerns me.
4. I can play with the valves so it is noiseless, but the input and outlet flow are reduced accordingly. I am still not sure I buy that even at fulll siphon that a 1"{ pipe will flow 2k gph..I will do more research on this as I am really confused now lol

I understand that it is air getting in that causes the noise. However, I cannot with my current config adjust to the requirements.

My CPR has simple strainers on the intake and simple sponge fits over these. I assume I will have to convert to upside down elbows like Bean? Or at least replace the strainers with pvc pipe?

Appreciate all of the help.

[Gilles]

Did you see this post?

It has (in my eyes) a better explanation then BeanAnimals own page.

[Biollante]

Hi Gerry,

“Noise” is in the ear of the beholder to misquote Plato yet again.

To be clear I am not saying a single 1” pipe is carrying all of the water these arrangements are indeed multi pipe arrangements, I assume in this case two 1-inch pipes are in use, one siphon, one open channel. Actually, there is no real limit to the number of siphon into a manifold that could be used as long as there is one open channel pipe.

My calculations and experience are with runs less than 7-feet, thermoplastic PVC and CPVC pipes Schedule 40, assuming Hazen-Williams coefficient of 150, drilled through the back or straight through the bottom of the tank with minimum 1½” bulkheads correctly reduced.

The presumption is that the siphon is carrying the majority of the water and the open channel is never handling more than 12.5% of the flow. Keeping the open channel flow at 10% or less is the easiest way to avoid noise.

The calculations and experience assume low turbulence behind the weir (intake area)

For lengths of pipe greater than 10-feet, for instance if someone wanted, the sump in a basement, then friction losses of would need to be accounted for.

For a siphon as in A Completely Silent Overflow - Is It Possible? From the Glass Reef that is up and over, the total volume carried is reduced by the bends.

Probably not worth the time and effort to do the arithmetic, since your internet sources must be correct and obviously all the published data are incorrect.

I stand by my experience and calculations.

Look I know the Sheriff of the Internet wants me thrown off the internet for using published data…

I do not mean to get in the way of anyone’s enjoyment of the hobby or interfere with cherished beliefs.

Biollante

[jcgd]

I personally run about 600-700 gph through my full syphon. 1" bulkheads and 1" pipe and my gate valve is maybe 1/3 or the way open. I can adjust it finely enough that not even a trickle goes down the open standpipe, but only for a few hours before a leaf or other forces change the balance ever so slightly. No need for 10% down the secondary though. I usually have drips after cleaning my screen and a trickle after a few days of debris restricting the flow through the full syphon.

[BigFlusher]

Using Hazen-Williams equation a 1” PVC pipe with a pipe slope of 1 (vertical) using 150 friction coefficient and a drop of 5’ the velocity is almost 17.25 ft/sec and 2533-gph

Bio may be a giant PITA, but has a bad habit of being right.