# pvc flow rates



## afoctober2 (Apr 7, 2007)

I"m planning on building a sump for my 90 gallon tank I have a quiet one 3000 pump its rated at 780gph with 10ft of head it has 1in fittings on it.

I plan on using this style of pvc overflow on my tank 
http://www.aquariumlife.net/projects/di ... ow/120.asp

I don't know what size pvc to use on the overflow I know my pump won't push out 780gph that its rated for. If I were to keep it at around 4ft head would be somewhere in the 500+ range hopefully figuring in the elbows in the pvc .

With that said I looked around and 1in pvc as a overflow is rated for 600gph. I know that isn't possible the hose barb would cut down the ID to like 3/4.

If the pump had 1in pvc on the pump and if the overflow was 1 1/4 would that match up better or possibly having 2 3/4 ?


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## Mcdaphnia (Dec 16, 2003)

If you think your pump may be more powerful than the overflow, you can put a ball valve-controlled tee in the return line, and divert enough of the water back through the sump again to run the system safely. You will still get the full benefit of the flow rate through the filter media in the sump by giving part of flow a double pass through the sump and filter media.

Keeping the flow through the overflow brisk helps prevent the buildup of gasses in the tube that can eventually break the siphon in overbuilt or underpowered overflows.


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## KaiserSousay (Nov 2, 2008)

> double pass through the sump and filter media.


Great idea.. :thumb: 
Wish I saw this earlier  
Off to lowes for more fittings


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## Hoosier Tank (May 8, 2007)

I had saved this for reference but don't remember where it came from...


> For a drain overflow (not siphon), the flow for various diameters of pipe is:
> .75" = 325gph
> 1" = 600gph
> 1.25"= 900gph
> ...


Notice the last statement, you won't get these amounts siphoning up and over the back of the tank.
Also two 3/4" would flow less that a 1 1/4" even though their comined total should be 1 1/2"... As far as the reduction in size of the ID caused by the hose barbs, you can buy the next size up hose barbs to get the right inner diameter and threaded fittings with ruducer bushings to adapt them to whatever pipe diameter you choose.
True statement that too large of U-tubes slows the flow to the point bubbles can collect and eventually break your siphon.


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## afoctober2 (Apr 7, 2007)

Should I go and set it all up with 1in pvc and see how it runs if the pump is faster than add the T.


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## willny1 (Nov 17, 2008)

You can do that, but having the ball valve T will help you fine tune it and have a little more peace of mind. Just make sure you test the system if you can. You can use a garden hose in the bathtub to test a "power out".

Also, don't glue anything until you are certain everything works.


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## afoctober2 (Apr 7, 2007)

Is this what you guys are talking about?










Is there any chance that adding that would slow down the filter to much and overflow the sump?


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## willny1 (Nov 17, 2008)

Yes, a 3 way ball valve.

Shouldn't slow the water flow down unless you have a 4 year old strong enough who likes to turn knobs. :drooling:


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## afoctober2 (Apr 7, 2007)

1yr old is close enough to it for me. Hitting stuff against the glass luckily nothing hard.

I think I will try 1 and 1 pvc first if that doesn't seem to be flowing good I will try the T ball valve.

When a sump is running how much water should be in it? If the pump is going to fast will it basically be almost empty all the time? Lastly where would I buy that T valve I've been looking around stores for a while getting an idea of parts I haven't seen these in menards, lowes, or home depot.


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## Mcdaphnia (Dec 16, 2003)

afoctober2 said:


> Is this what you guys are talking about?
> 
> ....
> 
> Is there any chance that adding that would slow down the filter to much and overflow the sump?


That 3-way might work, but using a wye or tee and then putting a straight ball valve on the backflow line coming from that wye or tee is the way I have always seen it done, except by people who put ball valves everywhere. That's how I ended up with a box full of used ball valves and gate valves.

As to slowing down the filter, isn't the filter on top of or in the sump? Extra water should be speeding it up. The bypass water is only recirculating within the sump, so it should not contribute to an overflow. In case of power outage, be sure there is a siphon break above the tank water level so that the tank water won't backflow through the pump and this bypass line.


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## mithesaint (Oct 31, 2006)

If I were in your shoes, I'd probably make two 3/4 " overflows. Redundancy is nice. If a single overflow gets partially or totally blocked, then you're going to have a flood. If you have two over flows, you have a better chance of catching the problem. I'm using a Quiet one 4000 @ 5' head with two 1' overflows. I've had zero issues thus far this way. Even restarted unattended while I was gone on vacation :dancing: Noise is another story, but I digress...

I've never understood putting a ball valve downstream of the pump. I know that it won't hurt the pump, but why would you want to limit GPH? If one over flow isn't enough....go bigger or get a second. Maybe I'm missing something.

You might want to put together that overflow design sooner rather than later, and make sure it works. From what I've read, a design like that won't restart on it's own after a power outage. As soon as the water level drops below the end of the blue pipe, your siphon is broken and won't restart on it's own. Maybe I misunderstood the design...I guess they're controlling the water level with the height of the yellow tee/green elbow, but I think that might impact how much siphon you can generate. Not sure. Good luck.


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## afoctober2 (Apr 7, 2007)

I was thinking the return and overflow would be on the sides. I see a lot with it going through the lid but seems like it be easier to clean filter media while running if the lid didn't have anything going through it.


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## auratum (Jul 6, 2006)

Another thing to consider is that there are different thicknesses of PVC pipe. There is at least two wall thicknesses for most of the smaller pipes - you can get thick wall or thin wall. For all of the overflows I have built I try to use the thinnest wall pipe as it has larger internal area for flow. The outside diameter is the same so all the elbows and tees are the same, but you can get more flow through the pipe (plus it is a little cheaper at Lowe's).

I would build it our of 1-1/4" pipe. I always want the overflow oversized to maximize flow through the system - bypassing flow just wastes energy.

Patrick


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## willny1 (Nov 17, 2008)

Do what I did. I have a 55 gallon.

my pump at 4 foot head is putting out 540 GPH.

What I did was put a piece of rubber 3/4" rubber vinyl tubing over the outlet barb for my pump. (My outlet barb is 3/4") The piece was only about an inch long just enought to cover the barb.

Then I put 1 " I.D. rubber vinyl tubing over that and up to the top of my tank into a home made spray bar. That will increase your pump flow. Less restrictions from the PVC 90 degree elbows and what not.

As far as the over flow goes, I would 1 inch 200 psi PVC. Its the thinner one and has a bigger I.D.

Regular schedule 40 PVC is about 440 PSI and has thicker with less I.D. space. So you get more flow with the first one. (every gallon counts :thumb: )

I just tested my system. 540 GPH with a CA1800 pump. 1 inch PVC overflow. 5 feet of rubber vinyl tubing for my return. :fish:


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## afoctober2 (Apr 7, 2007)

where do you find 20pvc I think everything i saw was 40


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## willny1 (Nov 17, 2008)

Home depot didn't have it so I went to Lowe's. If you can't find it at these places, a plumbing supply shop should definitely have it. Maybe a local hardware store.


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## afoctober2 (Apr 7, 2007)

I might try out ace hardware there always organized. Usually at the home depot or menards i go to by me its like an easter egg hunt nothing is in the bin its supposed to be in.


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## willny1 (Nov 17, 2008)

Yeah, it's like that at the one near me also. The pipe is inexpensive. was like 2.75 for a 10 footer.


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## afoctober2 (Apr 7, 2007)

I went to ace all they had was sch 80 pvc and a lot higher prices 7.79 for ball valves


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## KaiserSousay (Nov 2, 2008)

Could be I am wrong (it could happen :-? )
But, 1 1/4id pipe is 1 1/4id weather it is sch40, sch80,iron,galvanised etc..
All that changes is the O.D.


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## willny1 (Nov 17, 2008)

...


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## willny1 (Nov 17, 2008)

http://www.harvel.com/pipepvc-sch40-80-dim.asp

O.D. stays the same


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