16 July 2024 Finishing Up my OB Pool

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I suspect the returns are plumbed in series and why the first one is getting most of the flow rate causing the extra overflow and ripples in the local area near the return. Plus it is at a higher elevation as well.

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I would tie in the filter pump suction to the infinity edge suction line with a 3” line so that you can pull from the trough rather than the pool main drain so that you can have skimming action with the filter pump.
 
I think they will need to restrict the flow on the closest return anyway. If they are 2" eyeballs and 234 GPM total, then the flow imbalance is as follows:

Return #1: 93 GPM
Return #2: 60 GPM
Return #3: 43 GPM
Return #4: 38 GPM
 
My point is that the highest flow rate return is the one that is at the highest elevation and if you want to get rid of the ripples caused by that return, you will need to restrict it some.

But even with all the eyeballs at 2", the total head curve of that section of plumbing is only 0.000112.
 
Maybe convert the pool main drain into a return to improve flow.

You can use the trough suction for filtration.

You can use valves so that you can choose to use the pool main drain as a suction or as a return.

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mas985 said:
My point is that the highest flow rate return is the one that is at the highest elevation and if you want to get rid of the ripples caused by that return, you will need to restrict it some.
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I would try it without restriction to see how it looks and then maybe add a restriction to see which looks better.

The restriction increases velocity, so you get a smaller diameter more forceful jet of water, so it seems like it would reduce flow but not decrease ripples.

Maybe use some sort of fitting that diffuses the water to reduce the jet effect.
 

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mas985 said:
I thought you said there were four floor returns for the IE pump? What is the internal diameter of those 4 pipes?

The spa and normal pool returns are not relevant as they are on a separate loop.

The original drawing does not show these floor returns:

View attachment 585429
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That's correct, I added these during construction. I did quite a few sub contractor inspections pre-qualifying the forming and steel subs that had experience doing very high end infinity walls. I would get the locations of work in progress and show up on "surprise visits" to see the quality of construction before I let them bid. Every one I visited had the floor returns. I spoke with one of the engineers that happened to be on site and he said this makes their walls work much better so they do it on all their infinity walls now. Made sense to me and it is actually performing well for me. None of the other pools combined it with the zero edge like I have though. The pool now has a lot more cross-sectional area in the returns than the original design and it also has 66% more horse power.

Chris
 
JamesW said:
The other returns are restricted causing more flow to go to the open 2" pipe.

Removing the restrictions should even out the flow and improve total flow.
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Yes, that's clearly the case. I can easily remove the other 3 and see how that works. May need to get my dive gear on... think I've got about 500# left in the tank from last dive. I was actually thinking to even it out by adding an eyeball just because it's easier from where I am now. But I see your point.
 
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Try with no fittings in any of the returns.

I would probably convert the main drain into a return and just pull from the trough for the filtration.

If you tie in the filter pump to the 4" trough suction, you will need a check valve on the suction line to prevent backflow when the pump is off.

When pulling from the main drain, you do not get any skimming action.
 
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JamesW said:
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.
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JamesW said:
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.
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JamesW said:
5/16" = 201 gpm. This is probably what you can get with just the 5 hp pump running at or near full speed.
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If you are using the 4" trough suction for both pumps, I would probably limit the suction to about 17 feet of head, which is 7.36 psi or 15" of Mercury on a vacuum gauge.
 
JamesW said:
Try with no fittings in any of the returns.

I would probably convert the main drain into a return and just pull from the trough for the filtration.

If you tie in the filter pump to the 4" trough suction, you will need a check valve on the suction line to prevent backflow when the pump is off.

When pulling from the main drain, you do not get any skimming action.
Click to expand...
More good ideas to play with for the future. Thanks. Yes I would put a check valve in there anyway. I bought one but didn't install it yet. Will need to if I take suction off the trough for sure.
 
JamesW said:
Try with no fittings in any of the returns.

I would probably convert the main drain into a return and just pull from the trough for the filtration.

If you tie in the filter pump to the 4" trough suction, you will need a check valve on the suction line to prevent backflow when the pump is off.

When pulling from the main drain, you do not get any skimming action.
Click to expand...
I get plenty of skimming from the gutters. With this design the entire pool is essentially a skimmer.
 
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