# Thread: Infinity edge plumbing etc.

1. ## Infinity edge plumbing etc.

Hello all,

I am embarking on a pool build in our home in Mexico. That said, I am trying to educate myself on infinity edge pools. Does anyone have a basic plumbing schematic with pipe diameters and volume requirements? This pool will be about 15,000 gals with approximately 30 feet of negative edge.

I have a basis for understanding a normal pool install from my last pool build. This being a negative edge has me researching the trough volume, plumbing diameters and general data concerning a negative edge pool.

3. ## Re: Infinity edge plumbing etc.

Well, I'm not a builder but I'll tell you what I know:

First, be sure you have as sharp an edge as possible on the pool side to allow the water to pull away from the surface as it goes over.

Second, you need about 1/4" of lift for every 3' of drop from the edge to the trough. The further the water has to drop the more likely it is to start coming apart, so the more water has to be pushed over. For every 1/4" of lift you need 10 gpm per foot of edge. So...

30' is a BIG edge. That will require 300 GPM just for a 3' drop, 600 for 6', 900 for 9', etc.

Now to size the trough:

First, I'll assume at your size that your surface area is about 16 x 32, or roughly 500 sq ft. And we know you need at least 1/4" of lift in the whole pool to push over the edge. Since there are 7.48 gallons in a cubic foot, we can divide by 48 to get down to 1/4". So 1/4" of water is .156 gallons per square foot. You have 500 square feet, so that means you need to add 78 gallons of water per 3' of drop. This is called your "water in transit", or the water that will still be moving once you turn the pump for the edge off.

Next, you need to consider bather surge (max amount of water displaced from swimmers), which as a rule is 2" which through the above calculations works out to 620 gallons.

If you have a spa attached to the pool it is a good idea to add the gallons for it as well, just as a precaution. I'll assume no spa here.

You'll need your trough to be about 1' wider than the edge itself to compensate for water spreading out from the wind, so 31' total, and you need it to extend far enough to catch the water. Size this based on your drop. 3' drop will fall 1' from the wall, 6' will fall 2', 12' will fall slightly less than 3' away. This is all based on the 1/4" of water per 3' of drop rule.

So let's just say we've now got a 31' long by 2' wide trough, and a 3' drop from the pool to the trough. That gives us 62' square feet. We need to compensate for:
Water in transit = 78 gallons
Bather surge = 620
Spa volume = 0 (i assume)
So that total is about 700 gallons. Divide that by 7.48 to get the necessary cubic feet (~94). Divide that by your square footage (94/62 = ~1.5). That's the depth required to compensate for all the water that could spill over. You want to add an extra foot to this to be sure that when running the trough does not start to create a vortex and draw air through the drains. So your total trough depth should be 2.5'. Call it 3' since you probably won't be full to the top.

To get your 300 GPM you'll need multiple pumps. Theoretically 2 3hp pumps could do it, but you'd probably need three. You'll also have multiple main drains since they should only operate at 1.5 FPS max. That's only 20 GPM in 2" pipe, so you'll want to think about some larger diameter plumbing (3 or 4").

Hope this helps!

4. ## Re: Infinity edge plumbing etc.

Thank you very much it does help. I have to now go to my neighbor who has a 30' + - negative edge and is acheving the effect with one 3hp pump. Perhaps the head is much less.

Thanks again

5. ## Re: Infinity edge plumbing etc.

300 GPM is only necessary if you want a `sheet` of water to fall off your edge into your trough. I have seen projects with over 100` of edge powered by a half HP pump.

If you are not concerned with the `sheet` action of the water spilling over the edge, you can base your numbers differently. The starting point is how tight you expect your edge tolerance - or how flat your edge will be. If you can aim for an eighth of an inch edge tolerance in a 16` X 32` pool, you`ve only got to push 40 GPM over the edge to `wet` the entire edge.

I would make the catch basin 32`X 2`X 3`deep and use several main drains. If the water level gets too low in the basin you don`t want to hear the main drains vortexing in 6 inches of water.

You also need to think about auto-fills, overflows, hartford loops and redundant check valves and always oversize your suction lines. If you find that the pump can`t push enough water over the edge you don`t want small plumbing to bottleneck your ability to up-size the pump to achieve your effect.

The design of the weir wall is also very important and must use the proper materials and be waterproofed in the correct manner.

6. ## Re: Infinity edge plumbing etc.

Originally Posted by Waterworks
300 GPM is only necessary if you want a `sheet` of water to fall off your edge into your trough. I have seen projects with over 100` of edge powered by a half HP pump.
...and 1 1/2" plumbing. Yes they exist, but it makes you feel like you're watching a Viagra commercial. Women will be more impressed with you and you'll be more successful in life if you have a solid, raging sheet of water.

7. ## Re: Infinity edge plumbing etc.

Well, no, those projects would be using 2.5 - 3" suction plumbing and water velocities of 2-4 fps. And if the edge effect is located in an area that you can't even see, what's the point of having some huge loud effect, and paying for it. And, depending on the material used on the backside of the weir wall you might want to show it off, rather than obscuring it with a big curtain of water.

My guess is that women would prefer all the extra money you have in your bank account from the savings achieved by using one half HP pump rather than 3 - 3 HP models.

8. ## Re: Infinity edge plumbing etc.

Thank you Waterworks,

I decided on a Intelliflo and then added an additional 2 hp pump for a water feature. Both will operate from the catch basin and the Intelliflo will be valved to switch to the pool drains for cleaning cycles. I also doubt the water feature would be used without the infinity edge active. That gives me the option of 5 hp with 2 2.5 lines on four drains from the catch basin.

I did the math and it apears that will be enough to raise the water more than .200" along the weir. I would hope that is enough water to get the desired effect. Actually I hope to be able to get the desired effect with the intelliflo alone but am adding the water feature pick up from the catch basin just in case.

9. ## Re: Infinity edge plumbing etc.

A cool thing to do both to address the issue AND impress the ladies would be to buy an Intelliflo and either leave it in place so you could have either effect, or figure out what flow rate works best for you, size your pump accordingly, and use the Intelliflo for your filtration. You could even just go with a 4x160 if you were going to leave it on the spillover.

HOLY COW look at what you posted while I was writing this!

10. ## Re: Infinity edge plumbing etc.

Another nice feature of the Intelliflo is its ability to go into 'edge cleaning' mode and ramp up the speed every few hours automatically to send a bit more water over the edge to clean off any leaves or other dirt that might have settled onto the edge.

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