Silent and Failsafe Overflow System

[Drama]

Originally Posted by Drama

can you recommend a decent gate valve for 1 1/2" sch 40 slip. I've been searching around and get ranges from 14$ all the way into the hundreds. i would be comfortable spending 30 - 50$

never mind found some decent ones. thanks

[uncleof6]

Originally Posted by chiroken

Uncle, thanks again.

OK, so the waterfall height and water level in the overflow will basically work itself out, not something I am specifically measuring and planning beforehand. It will pretty much be determined by where I place the bulkhead and the depth of the overflow water will be determined by the width of the weir (same volume of water over different widths, get that) and as long as the top of the weir is level with the bottom of trim I won't see the waterline.

Well sorta, it sounds more complicated than it is though. The head height behind the weir (tank side) is determined by flow rate, and length of the weir. The water level in the overflow is determined by the 'internal weir' height in the tee. Easier to say bulkhead height, though not exactly. So the height of the waterfall is the difference between the head height behind the weir, and the water level in the overflow.

The overall height of the box will be determined once I have the bulkhead and elbow in place, plus clearance under the elbow.

Roger that...

The outlet of the pump is threaded so I want a threaded bushing to get myself to 1". So 3/4" thread x 1" slip bushing basically (if this is even available). I hear you on the reliability of unions. What do you suggest just above the return pump to allow removal of the pump? (grinning to see if your answer is a hack saw again )

Hacksaw....ok ok could not resist... this is the one place a union comes in very handy, and in fact are obligatory. I use spa fittings. However, I use much larger pumps. Hunt around pool supply shops, if you want these, they can be had in 1".

Sound right?

Eventually

Oh, ignore the absurdity of the 2" gate valve on the intake: really pointless, [insert cheap ball valve here] but was the only 2" valve I had laying around at the time.

[Drama]

looks like some sort of weapon. lol

[DownwardDawg]

Greetings. Haven't posted in a while but I just ordered a new DSA 65 Pro to replace the 60 gal tank I have now. We are moving so I used the move as an excuse for a new tank. WTH.

Anyway, this DSA tank has 3 holes in a center overflow box. I want to go with the Beananimal overflow but I'm not exactly sure just how to do it in a regular overflow box. I know the popular answer will be to go read the thread but I'm lazy and I'm not reading through 678,000,000,000,000 posts to find an answer!!

1) Are the elbows required or can you just use straight pipe? My 125 runs dual Herbie's but the pipes are straight, no elbows
2) How high up in the box can the full siphon be? The ones in my Herbie system sit about halfway up in the box but are choked back by gate valves so the water level sits well above them.
3) Shouldn't the open channel drain be above the full siphon?
4) At what level does the tubing sit at that comes out of the top of the open channel.

[uncleof6]

Originally Posted by DownwardDawg

I know the popular answer will be to go read the thread but I'm lazy and I'm not reading through 678,000,000,000,000 posts to find an answer!!

Well that is fair enough. You probably will have to read < 100 posts, perhaps just within the last 10 pages, to find your answers, so that is 677,999,999,999,900 that you won't have to read. I can live with that...I am certain, that the few of us that have put considerable time and energy into this source of information, can live with that too...

[DownwardDawg]

Originally Posted by uncleof6

Well that is fair enough. You probably will have to read < 100 posts, perhaps just within the last 10 pages, to find your answers, so that is 677,999,999,999,900 that you won't have to read. I can live with that...I am certain, that the few of us that have put considerable time and energy into this source of information, can live with that too...

Hhhhmmmmm. I think that's fair enough. Last 10 pages.....
Thank you for pointing me in the right direction. That helps a bunch!

[Drama]

Gate valve showed up, thanks for pointing me in the right direction.

took this pic just to show how big it is, man those fingers are like hotdogs. Lol

[chiroken]

So go with a schedule 80 gate valve....got it. The main plumbing is to be schedule 40. Now, can I assume that schedule 40 outside diameter is consistent with schedule 80 so that my PVC piping will have the right fit into a schedule 80 fitting or valve? Is the OD consistent, just the ID different due to a thicker sch80 wall? Thx.

[BonsaiNut]

Originally Posted by oldsaltman

Should I be concerned with the 1/16" off level. My level said it was level but the water doesn't lie.

(1) When using a construction or spirit level, always level twice - reversing/flipping the level between measurements, so that you will balance out any inaccuracies in the tool. I have a 6' level that I use for pool tables and I always measure all four sides as well as the diagonals TWICE.

(2) For aquariums, use a water level. 100% accurate, and cheaper too I'll bet you could make one with even going to the store

[rEeFnWrX]

Originally Posted by uncleof6

Well sorta, it sounds more complicated than it is though. The head height behind the weir (tank side) is determined by flow rate, and length of the weir. The water level in the overflow is determined by the 'internal weir' height in the tee. Easier to say bulkhead height, though not exactly. So the height of the waterfall is the difference between the head height behind the weir, and the water level in the overflow.

Roger that...

Hacksaw....ok ok could not resist... this is the one place a union comes in very handy, and in fact are obligatory. I use spa fittings. However, I use much larger pumps. Hunt around pool supply shops, if you want these, they can be had in 1".

Eventually

Oh, ignore the absurdity of the 2" gate valve on the intake: really pointless, [insert cheap ball valve here] but was the only 2" valve I had laying around at the time.

Please correct me if I am wrong... However, from research and what pump manufactures have told me in the past. Is it not best to put your flow regulating valve on the outlet side of a pump.... Have always been told regulating the inlet side can cause premature wear and tear...

[samba]

Hi all. I have read quite a lot of this thread including at least the first 20 pages, but I can't seem to find the answer to my question. Is 5 mm clearance under the syphon elbow going to create problems? The overflow box is 95mm high and the weir lip is 1" below a rimless tank (36Lx18Wx24"H) with 1" plumbing throughout(no t pieces just elbows). The secondary is 12mm above the syphon and the emergency is about 10mm above the top of the down turned open drain. I will have the tube that comes out of the secondary sit about 10mm above the emergency and level with the lip of the weir.
Sound ok?

[jc286006]

hello all

i am putting this type of overflow on 2- 40B`s i know it has been said in previous posts that it isnt needed on that size tanks but that is what i am going to do because this type of overflow looks to be the easiest to get built and adjusted if instructions are followed.

the bulkheads i am using are 1 inch do i need to increase the drop pipe size to 1 1/2 inches or would 1 inch through out my build be sufficient.

the tanks are going to be stacked on top of each other in a custom built stand the top tank will have a fall of approximately 54 inches the lower tank will only have about a 28 to 30 inch fall into the sump tank.

the way they will be setup they will be straight down no elbows of any kind other than the elbows inside the overflow box and the elbow of the clean out Tee`s

what do you think 1 inch all the way through or increase to 1 1/2 after the bulkheads?

thanks for your suggestions
James

[uncleof6]

Originally Posted by rEeFnWrX

Please correct me if I am wrong... However, from research and what pump manufactures have told me in the past. Is it not best to put your flow regulating valve on the outlet side of a pump.... Have always been told regulating the inlet side can cause premature wear and tear...

That is correct. The image is obviously going to be misinterpreted, and that was alluded to when I posted it. The image was posted in reference to spa fittings not the valve. The image was originally taken for other purposes, that required that a valve be in place on the inlet, and that is the only 2" valve I had laying around....

"Oh, ignore the absurdity of the 2" gate valve on the intake: really pointless, [insert cheap ball valve here] but was the only 2" valve I had laying around at the time."

That said, there is nothing intrinsically wrong with a gate valve on the intake, other than it needs to be run full open, so it takes more than a 1/4 turn to shut off flow for pump removal. It is a mis-application of a gate valve, and it should be a ball valve; using a ball valve on the outlet is a mis-application of a ball valve. Ball valve: on/off. Gate valve: flow control.

[uncleof6]

Originally Posted by samba

Hi all. I have read quite a lot of this thread including at least the first 20 pages, but I can't seem to find the answer to my question. Is 5 mm clearance under the syphon elbow going to create problems? The overflow box is 95mm high and the weir lip is 1" below a rimless tank (36Lx18Wx24"H) with 1" plumbing throughout(no t pieces just elbows). The secondary is 12mm above the syphon and the emergency is about 10mm above the top of the down turned open drain. I will have the tube that comes out of the secondary sit about 10mm above the emergency and level with the lip of the weir.
Sound ok?

This is covered well (100's of times) both in this thread and otherwise. Although there is no standard for this, 19mm is what I recommend. Anything less is trying to make this as small as possible, and that is where problems begin.

There really is no reason to be putting the bulkheads higher or lower in relation to each other, and no reason for the open channel to be above the siphon, or the siphon below the open channel (however one wishes to view it). The issue that this solves, is due to implementation errors, that can be avoided, by attention to detail, and an understanding of how the system works.

[uncleof6]

Originally Posted by jc286006

hello all

i am putting this type of overflow on 2- 40B`s i know it has been said in previous posts that it isnt needed on that size tanks but that is what i am going to do because this type of overflow looks to be the easiest to get built and adjusted if instructions are followed.

the bulkheads i am using are 1 inch do i need to increase the drop pipe size to 1 1/2 inches or would 1 inch through out my build be sufficient.

the tanks are going to be stacked on top of each other in a custom built stand the top tank will have a fall of approximately 54 inches the lower tank will only have about a 28 to 30 inch fall into the sump tank.

the way they will be setup they will be straight down no elbows of any kind other than the elbows inside the overflow box and the elbow of the clean out Tee`s

what do you think 1 inch all the way through or increase to 1 1/2 after the bulkheads?

thanks for your suggestions
James

1" bulkhead has a flow capacity at 24" drop, of 1669gph. In 1" pipe, that flow can be expected to be down around 1200gph. In 1.5" pipe, 1500gph can be expected.

The only problem you can expect, with 1" pipe, is that it does not get any worse than running a 1" durso, in terms of keeping them quiet, and bubble free. Well...a 3/4" durso would be worse... I would suggests 1.25" pipe on the 1" bulkhead for the open channel.

[samba]

Please indulge me. My tank is only small so space is at a premium. Trying to get this box small as possible is important. Please explain if you would why this wouldn't work, and do the rest of the dimensions sound ok.

Many thanks.

[uncleof6]

Friction losses, with water moving into the pipe, through a relatively small opening.

The dimensions you have provided don't tell me anything about the setup at all, other than relative positions. Read back several pages and look for the dimensions that are posted, as being critical, and we can go from there. Usually, when someone gets more concerned about making things as small as possible, rather than putting function first, they end up with a system that won't work as intended, because the critical dimensions are wrong.

[tazdvl]

Originally Posted by uncleof6

Bush off the pump directly to 1". Don't pass go, do not collect two hundred dollars on the way...

I had read someplace that going larger on the output size is asking for cavitation problems with pumps. Don't know where I read that or if I even got it right. I do notice that seems like intakes are always bigger then outputs on pumps. And great googly moogly will someone please take a gander at my "coast to coast" idea in http://www.reefcentral.com/forums/sh....php?t=2429236 Please

[uncleof6]

Originally Posted by tazdvl

I had read someplace that going larger on the output size is asking for cavitation problems with pumps. Don't know where I read that or if I even got it right. I do notice that seems like intakes are always bigger then outputs on pumps. And great googly moogly will someone please take a gander at my "coast to coast" idea in http://www.reefcentral.com/forums/sh....php?t=2429236 Please

It depends on the type of pump, and the size of the inlet.

For external pumps, you do not want to increase the outlet pipe size larger than the intake pipe size. Doing so will cause the pump to cavitate. (pressure differentials.) But it is really easy to deal with this. Example: 3/4 inlet and outlet. We know that performance of the pump will increase, by increasing the outlet plumbing to 1". (Fluid Dynamics.) But this presents a dilema, a problem.

The inlet/outlet size does not determine the size of the plumbing needed for a given pump in a given system. Flow rate and friction loss do. (keeping it simple, but variables such as distance to the intake volute from the source is also involved; lifting water e.g. pump higher than the water level in the source container as well, etc.) The way to solve the cavitation dilema, with our imaginary pump above, is to increase the intake plumbing size to 1". Larger outlet, larger inlet, a large as you care to go. With each pipe size increase, the actual output of the pump will increase, with the limitation of static head height on the flow curve, and an understanding that a plumbing system without friction loss does not exist.

Submersible pumps are a different story. Since there is seldom, if ever, plumbing attached to the pump intake, the outlet pipe size rule does not apply, as the actual intake volute for the pump will always be flooded. Example: Mag Drive pumps 9.5 and larger require 1.5" outlet pipe to get any flow out of them.

***********************************************************

I am certain that your 'overflow' design will get water out of the tank, but I think you need to work on it a bit more...without getting into the pertinent fluid dynamics, (things such as friction loss, single body of water vs hole in the side of an overflow) how you going to support that thing? I saw it a day or so ago, but the amount of typing would give me a headache... Look into such endeavors as bridging dual corner overflows, (a related topic) vs complete removal of corner overflows and replacing with much better designs....

[jc286006]

thank you uncle for the suggestion i will use 1.25 inch for the plumbing then unless you see any benefit with me using 1.5 inch other than i have some laying around = cost savings is all?

[rEeFnWrX]

Originally Posted by uncleof6

Example: Mag Drive pumps 9.5 and larger require 1.5" outlet pipe to get any flow out of them.

Now this I do not believe to be correct at all...

I am no expert at all but the larger the outlet plumbing, the more dramatic the head pressure becomes...

A pump would have to push up twice as much "water weight" with 1.5" plumbing than it would with 3/4" plumbing... You have twice the water weight, moving slower...

[uncleof6]

Originally Posted by rEeFnWrX

Now this I do not believe to be correct at all...

I am no expert at all but the larger the outlet plumbing, the more dramatic the head pressure becomes...

A pump would have to push up twice as much "water weight" with 1.5" plumbing than it would with 3/4" plumbing... You have twice the water weight, moving slower...

With some things, it is far wiser to believe, than to not believe. However, when there is a natural science behind it, belief is not necessary. But yes, in a way you should not: 1.5" is the minimum size... I had never heard of such a thing, (such a large increase in pipe size being needed,) till it was put rather bluntly to me. I had always indicated it was prudent to increase the pipe size by one size. The mag drives are particuarly poorly engineered pumps...the flow increase is along the lines of several hundred gph.

I direct you to the Danner Mag 9.5 instructions, page 2 just below the bar graph:

http://www.dannermfg.com/Store/images/instructions/ZG100.pdf

Pressure and weight are not the same thing. Weight involves mass and the acceleration due to gravity, it is static, at rest. Water is a liquid, pressure is static or dynamic (in motion,) and though it does have mass, and is affected by acceleration due to gravity, that has nothing to do with head pressure. Folks very often get weight and pressure mixed up.

We have a 1" pipe, 100' tall. Filled all the way to the top with water. The pressure at the bottom of the pipe, (head pressure) is x. We move to the ocean, we go down 100', and we find that the pressure at that point is also x. Pressure at a given depth in a volumes of water, is equal, and it is equal in all directions, regardless of the size of the container, Not accounting for local ambient pressure. (Barometric pressure.) Though the weight of water in the ocean is far greater than the weight in our 1" pipe, at the same depth the pressure will be equal.

So from this, it can be seen that weight is not a factor (e.g. how much does the water in the pipe weigh.) Having a pump push water up 100' in 1" pipe, the pump will see the exact same head pressure as it would in the middle of the ocean at the same depth. However, the output of the pump will be greater in the open ocean, than it will be in the 1" pipe. The reason is friction loss, or loss in pressure due to being in contact with the pipe walls, in the 1" pipe. There are several terms for pressure in fluid dynamics, but none of them are related to weight.

Since this is dynamic, the natural science of this topic is called fluid dynamics, a subdiscipline of fluid mechanics, (deals with fluid flow) the natural science of liquids and gases in motion. More specifically it is Hydrodynamics...seperates it from Aerodynamics.

We are getting pretty far away from the topic in this thread, however, fluid dynamics is important in drain systems, as well as return systems.

[woodnaquanut]

Uncle speaks the truth. That's why a tall tank (other dimensions being the same) needs thicker glass/acrylic than a shallow tank.

[BeanAnimal]

Originally Posted by rEeFnWrX

Now this I do not believe to be correct at all...

I am no expert at all but the larger the outlet plumbing, the more dramatic the head pressure becomes...

A pump would have to push up twice as much "water weight" with 1.5" plumbing than it would with 3/4" plumbing... You have twice the water weight, moving slower...

This is a very common perception, but wholly incorrect. The pump does not see or understand the "weight" of the water column against it. The pump sees pressure differential between the suction (inlet) and discharge (output) side.

The pressure at the bottom of a 10 foot tall drinking straw is the same as the pressure at the bottom of a 10 foot swimming pool is the same as the pressure measured 10 feet deep in the worlds largest ocean.

[BeanAnimal]

Originally Posted by tazdvl

I had read someplace that going larger on the output size is asking for cavitation problems with pumps. Don't know where I read that or if I even got it right. I do notice that seems like intakes are always bigger then outputs on pumps.

Increasing the diameter of the discharge piping can only create cavitation if the suction side of the pump is restricting the ability of the pump to intake the amount of water it is capable of pumping.

If the suction piping is properly sized, then the pump will NOT cavitate. regardless of the size of the discharge plumbing.

It follows that if one restricts the suction side of the pump, then the discharge side must also be restricted to compensate for the lower pumping capacity, as otherwise the pump will cavitate.


As for you split PVC overflow... many folks have fiddled with setups like that but they never work out well. Ignoring the fabrication and placement issues, the "slot" becomes easily overwhelmed by water.