Plumbing Pipes

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,735
Pleasanton, CA
Pool Size
20000
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Plaster
Chlorine
Salt Water Generator
My own experience is that it takes close to 15 GPM/skimmer to ensure that debris makes it to the skimmer basket. At lower GPM, the debris tends to collect in the mouth of the skimmer but not make into the basket so anyone that starts swimming or the wind picks up (i.e. waves) tends to push the debris back out into the pool. Some skimmer manufactures give a 25 GPM minimum. Some venturi skimmers can go below 10 GPM.
 
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JamesW

TFP Expert
Mar 2, 2011
28,262
My own experience is that it takes close to 15 GPM/skimmer to ensure that debris makes it to the skimmer basket. At lower GPM, the debris tends to collect in the mouth of the skimmer but not make into the basket so anyone that starts swimming or the wind picks up (i.e. waves) tends to push the debris back out into the pool. Some skimmer manufactures give a 25 GPM minimum. Some venturi skimmers can go below 10 GPM.
Each system will need to be tuned to the optimum operation by checking the flow and then adjusting until it is working like the person wants.

Swimmers making waves can cause a lot of weir door banging and damage the doors.

During high use times with a lot of waves, it is probably a good idea to increase the flow to about 25 gpm per skimmer to avoid weir door damage and backflow of debris.

The increased flow is also good for sanitation as high bather loads create a lot of contamination that should be filtered.
 

mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,735
Pleasanton, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
The increased flow is also good for sanitation as high bather loads create a lot of contamination that should be filtered.
I don't believe filtering improves sanitation at all. Chlorine should kill anything before it even reaches the skimmer let alone the filter. TFP FC/CYA are set specifically for very fast bacteria kills. Once dead, moving it to the filter is not all that important, especially since it will take many days to filter "all" the water in a typical pool. However, there are a few bacteria that won't be killed by chlorine but many of those are too small to be trapped in a filter anyway.
 

JamesW

TFP Expert
Mar 2, 2011
28,262
When you get a lot of people in the water, they begin to shed all types of nasty particles that are at least potentially filterable.

Things like hair, skin cells, cryptosporidium, Giardia, fecal matter, lotions and body oils etc. can all be inadvertently ingested by people in the water.

In my opinion, the FC and filtration rate should be increased for high use times like a party etc.

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mas985

TFP Expert
LifeTime Supporter
May 3, 2007
14,735
Pleasanton, CA
Pool Size
20000
Surface
Plaster
Chlorine
Salt Water Generator
But again, those rates are for water passing through the filter and not for removal from all the pool water. That takes much much longer (>10 turnovers). It just isn't practical to expect a filter to remove bacteria in a timely fashion.
 

JamesW

TFP Expert
Mar 2, 2011
28,262
For a high use situation, I think that it is probably worthwhile to increase the flow rate while people are in the pool and then to keep it at an elevated rate for a while depending on the amount of matter that needs to be filtered.

Other maintenance items should also be addressed like cleaning all baskets, vacuuming, brushing, cleaning the filters etc.

If you want to get to 10 turnovers to get the filtration you want, you might as well get it done at a faster rate (within reason).

If you go from 20 gpm to 40 gpm, you will get to 10 turnovers twice as fast.

It might not help on the same day, but it should help for subsequent days when the water has had a chance to hit at least 4 to 10 turnovers.

Increasing the FC before and after can also be helpful.
 

Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,257
NY
I LOVE when you 2 debate the science of it all, It’s fascinating to read. But y’all miss the real world parameters of a get together.

Not wanting to listen to ‘Daddddddddddeeeeeeee turn the jets up HIGH’ every 3 minutes means the pump will be running full RPM throughout. 😁

(which I agree can only help get more oils/lotions/exfoliated skin/ etc to the filter. Maybe not needed but certainly not harmful either).
 
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Newdude

Gold Supporter
TFP Guide
Jun 16, 2019
11,257
NY
Wait !!! I forgot how much you two need science and math so hereyago.

full pump speed = complaints / 9.3
Complaints come in every 27.9 minutes netting 24.9 minutes of peace.

then you only have to comfirm that, yes sweetie, the pump is on high every half hour. Every other 30 minute increment you will confirm that ‘no, they don’t go higher’.
 
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