SWG sizing

[Poolecw]

I have read to go at least 2x larger in size than you need and I understand the reason as to why.

However, if I go with a variable speed pump and plan to run on low for extended periods, would the correctly sized SWG suffice?

 

[ajw22]

Pump speed has no relationship to SWG sizing. You just need enough water flow to turn on the SWG with the flow switch.

Get at least a 2X SWG and the bigger the better. There is savings in buying in bulk.

How many gallons will your pool be?

 

[Poolecw]

Pump speed has no relationship to SWG sizing. You just need enough water flow to turn on the SWG with the flow switch.

Get at least a 2X SWG and the bigger the better. There is savings in buying in bulk.

How many gallons will your pool be?

It's a rectangular 18x36, so the volume is around 20k gal.

I just want to be sure my old school pool builder installs the right size equipment.

 

[mknauss]

Get a 40K rated SWCG.

 

[splashpad]

However, if I go with a variable speed pump and plan to run on low for extended periods, would the correctly sized SWG suffice?

That would actually lower it's life Because a cell's life is estimated by hours of operation at 100%. (to over simplify)
The output of the smaller cell at lower percentage may not be enough to sustain pool's chlorine needs. (depending on swimmers & sun exposure)

It's a rectangular 18x36, so the volume is around 20k gal.

I just want to be sure my old school pool builder installs the right size equipment.

Absolutely! Knowledge is power!

 

[ajw22]

That would actually lower it's life Because a cell's life is estimated by hours of operation at 100%. (to over simplify)
The output of the smaller cell at lower percentage may not be enough to sustain pool's chlorine needs. (depending on swimmers & sun exposure)

The life of a cell is from the amount of CL generated, not the hours run or the water flow through it. If your pool water volume needs 1 lbs of chlorine a day it does not matter if the cell generates it in 6 hours or 24 hours. SWG's egenrate chlorine slowly so you have a minimum runtime to get the desired CL generated. 6 hours at 100% or 12 hours at 50% or 24 hours at 25% all use the same amount of cell life.