16 July 2024 Finishing Up my OB Pool

[JamesW]

I would tie in the filtration pump suction to the 4" Infinity Edge suction so that you can run the edge from the filtration pump if you want.

You can run both pumps at the same time to increase the flow over the edge to about 375 GPM, which would give you about 7/16" lift.

However, that puts the flow over 6 feet per second.

Pipe Size and Flow Rates.​

You want to keep the water velocity below 6 ft/sec on the suction and below 8 ft/sec on the pressure side of the pump.

Pipe Size	6 ft/sec	8 ft/sec
1.5"	38 GPM	51 GPM
2"	63 GPM	84 GPM
2.5	90 GPM	119 GPM
3.0"	138 GPM	184 GPM
4.0"	235 GPM	312 GPM

Below was my original suggestion of (3) 3" lines, which would have allowed for about 414 GPM at 6 feet per second.

Blue = Main Drains.
Green = 2" or 2.5" PVC pipe.
Red = 3" PVC pipe.
Black dot = Check Valve.
Purple dot = Jandy NeverLube 2.5" (Inside) x 3" (Fitting Outside) two-way valve or 2" x 2.5" Jandy NeverLube two-way valves for skimmers and pool main drain.
There will be (2) 2.5" (Inside) x 3" (Fitting Outside) Jandy NeverLube Check valves after the Infinity Pump and (2) 3" Jandy NeverLube Check valves before the Filter Pump Suction Manifold.

This will allow you to adjust the edge flow and filter flow independently.

 

[mas985]

With all 4" pipe and nothing else, you should be able to hit about 275 GPM at 3,450 RPM.

Still need a check valve right? Max size for Jandy is 3" so bushings and fittings are required at a minimum.

The results I posted earlier without the heater but with a check valve and a bit of 3" plumbing shows a flow rate of a little less than 230 GPM which is below 6ft/sec. But given no one is swimming in the trough, 8 ft/sec would be acceptable as well.

Also, changing the plumbing at this point after the pool has been built seems like it would be pretty expensive.

 

[JamesW]

How much flow can the edge get with both pumps pulling from the trough on the 4" pipe?

 

[mas985]

The drawing show a separate main drain in the pool for the pool filter. The edge flow is based upon a single pump.

 

[JamesW]

How far from the basin to the pump?

120' based on site plan and including bends.

If we assume (7) 90 degree fittings, then the total equivalent length comes out to 190 feet, which is about 6.15 feet of dynamic head loss.

Then, you need to add the static head loss which is the distance from the pump inlet to the lowest water level in the basin.

If you tie in both pumps, you can run the edge from either pump and you can probably get up to 300 GPM combined.

 

[mas985]

I think you are really light on your assumptions.

First, you show no 3" pipe and there will be some because it is already installed and unlikely to change. Plus there is the 3" check valve.

Per the drawing, the pipe length alone is close to 90' in each direction without elevation changes so I assumed 100' in each direction. The drawing shows 6 90s from the basin to pad but there are a couple of elevation changes @ 2 90s each. Plus a couple 90s above ground level as well so I get 10 90s in each direction. Also, if you include return size reductions, that will also add head.

So my calculations come out to 227 GPM @ 9' of dynamic head + 5.5' of static head = 14.5' of total head.

Again, all of the assumptions are shown here:

Pool Pump Tools v028 - setsailsoon

docs.google.com

I am happy to adjust them if any are incorrect.

 

[JamesW]

At 328 gpm, the suction head loss will be about 12 (dynamic) + 5 feet (Static) = 17 feet.

The Infinity return will be about 228 gpm at 6 feet of loss for about 23 feet of total head loss.

Even if you add 7 feet for check valves, that is only 30 feet of head loss for the 5 HP pump.

The pool filter return will be about 100 gpm.

 

[JamesW]

You can install a vacuum gauge on the line to see what the value actually is.

In any case, I would tie in the filter pump to the 4" line and that way you can run the edge from either pump.

You can run both pumps at the same time as long as the suction does not hit 14 feet of head loss, which is where the pumps might begin to have problems.

If you are going to run the filter pump anyway, you might as well use it to move water over the wall.

You start out with 34 feet of NPSHa at zero flow and the head loss reduces this.

So, at 14 feet of head loss, you have 20 feet of NPSHa.

If we assume that the 5 hp needs 20 feet of NPSHr (Net Positive Suction Head Required), then the flow is probably limited to 280 gpm using both pumps.

14 - 5 = 9 feet dynamic available.

If the 5 hp pump can do 210 gpm, then the filter pump can add about 70 gpm.

Sell Sheet | IntelliFlo3 VSF Pool Pump

online.flippingbook.com

 

[JamesW]

It really depends on how much lift you want.

That's a subjective decision.

You might be happy with 1/8" and you might prefer 1/2".

You might be able to put both pumps on the 4" line and run them both at full speed and that is the best you can do and the flow is what it is.

It depends on where the pumps will begin to cavitate and what the actual head loss is on the suction and return.

If the pumps cavitate at full speed, you will need to turn them down until the cavitation stops.

 

[JamesW]

264 GPM/32 = 8.26 gpm per linear foot, which will give about 3/8" lift. This is probably what you can get with both pumps.

If the wall top is perfectly straight and level, then a 1/8" lift (51 GPM) might be acceptable.

I suspect that you will probably want at least 1/4" of lift for good effect, which is 32 x 4.5 = 144 gpm.

5/16" = 201 gpm. This is probably what you can get with just the 5 hp pump running at or near full speed.

 

[mas985]

The flow rate requirement for an IE is usually dependent on the tolerance of the edge and how close it is to perfect level. 1/16th of an inch is pretty level and a good tile guy should easily manage that so an 1/8th inch average overflow should keep the wall uniformly wet. An IE with a single pump should handle that easily with plenty of margin.

 

[JamesW]

Some people like the look of more flow, so it can be subjective.

Also, if you have a lot of people jumping in and causing water to go over the edge in large waves, you need to increase the flow to keep the trough from overflowing.

The average person is about 18 gallons and when someone jumps in, you can get 10s of gallons going over the edge.

So, the amount of flow has to be able to maintain the extra water in the pool.

 

[mas985]

Once the edge is wet, you really won't notice the height that much.

But I agree, emptying the trough is important.

 

[JamesW]

18' x 32 ' x 1" = 358 gallons

1 gallon = 0.0027933"

5 people in the pool require about 90 gallons to keep the extra water in the pool plus maybe 20 gallons to account for waves.

110 gallons = 0.3072" = 5/16" = 200GPM.

 

[JamesW]

Once the edge is wet, you really won't notice the height that much.

The effect is better when you have more lift because at low lift, you can see the wall.

With more height, the wall disappears more and you get a better "Infinity" effect.

 

[setsailsoon]

Isn't the pool water level about at about the same height as the pump pad?

Yes it's close... about 12" drop. Pool pad is elevated to roughly 31' 7" Pool zero edge is about 30'7"

Is this drawing still accurate?

It's close. Basin level is 67" drop from pump inlet at low level

16 July 2024 Finishing Up my OB Pool

Impossible for me to evaluate what is missing without seeing all the documents. Your list had pavers and plaster but not coping and tile. Hmmm… PS Yes great idea to add a suction port in case I decide to go back to suction cleaner. But my base plan is to use robot. Even have a special pipe...

www.troublefreepool.com

I used that for the IE plumbing and put together a rough head loss model for plumbing with the heater in-line and one for the heater bypassed and one without the heater at all.

Pool Pump Tools v028 - setsailsoon

docs.google.com

The results are plotted below. Bypassing the heater helps but not as much as eliminating the heater all together. How long is the edge? What is the tolerance on the edge height?


View attachment 583176

 

[setsailsoon]

Can you use the filtration system for heating and the 5 hp for jets at the same time?

Do you have 2 suctions and 2 returns?

I can do that but will require some plumbing changes. I have 3 suctions - infinity basin, main pool, spa. Also have 3 returns - sun deck bubblers, floor returns in the main pool, spa+main pool non-floor returns.

 

[setsailsoon]

18' x 32 ' x 1" = 358 gallons

1 gallon = 0.0027933"

5 people in the pool require about 90 gallons to keep the extra water in the pool plus maybe 20 gallons to account for waves.

110 gallons = 0.3072" = 5/16" = 200GPM.

Yes and we can easily accommodate the surge. The outer 6" tile tilts up at the back ~1.5". The infinity basin is about 1500 and is 36" usable depth so 5 people are a couple inches in the basin.

 

[JamesW]

I can do that but will require some plumbing changes. I have 3 suctions - infinity basin, main pool, spa.

To heat the spa with the filtration system and run the jets with the 5 hp pump, you would need 2 spa suctions and 2 spa returns.

I would change the filter pump to 3 hp and install a 3.5 to 5 lb check valve bypass on the heater.

 

[setsailsoon]

The effect is better when you have more lift because at low lift, you can see the wall.

With more height, the wall disappears more and you get a better "Infinity" effect.

When you first pointed out the weir calcs I realized I would need to set this up with an infinity only mode. The entire inner wall of the pool is very close to 1/16" tolerance. The 5/16" is for the infinity wall 32' long so if I let it overflow all around the pool we're a LOT longer and the height over the wall is very thin. So I had pipe sealed in the gutter on each end so I can close a valve on each pipe, fill the gutter and allow all the water to go over the infinity wall. Under this condition the water actually rises up the tilted tiles out side the pool without flooding the deck. I really appreciated you sending me those calcs. If I hadn't seen those I could have ended up with a pool that wouldn't work too well. As it is, I can already tell it's gonna be fabulous when I get the pipes sealed in (supposed to be tomorrow).