SWG for ~20,000 pool, also max temp?


Well-known member
Oct 31, 2014
Bay Area, California
I am thinking of converting my new pool to salt water.

I've been looking at the Hayward AR9 system, which is listed at 25,000 gallons. How is this measured? With the pump running a certain number of hours per day? Ideally I would only be running the pump while the solar system would be effective. The AR15 system which is quoted for 40,000 gallons is only like 100 bucks more

Also is there a temperature when SWG's become ineffective? Sometimes I'd like to be able to heat the pool to a comfortable night temperature, meaning 90 or higher degrees.


TFP Guide
In The Industry
May 15, 2007
New Brunswick Canada
Firstly how big is your pool, we recommend here that minimum is twice the size of your pool, that allows you to run swg and pump on a timer. AR9 only puts out .9 lb cl2 a day...ar15 puts out 1.4 lb a day


TFP Expert
LifeTime Supporter
Jun 24, 2011
Long Beach, CA
The high temperature will not be the problem, SWG's will not produce chlorine when the water temperature drops too low, around 50 degrees or so.


TFP Expert
LifeTime Supporter
May 3, 2007
Pleasanton, CA
Given we are in the same area and have the same pool size, with a T-15 cell I can get my run time down to about 4 hours at 90-95% SWG setting and consistently maintain a 4 ppm FC level (80 ppm CYA) during the summer (peak load).

As for heat, higher water temps tend to increase the FC consumption so you might need to set the SWG a little higher.


LifeTime Supporter
TFP Guide
Jun 12, 2011
That 20,00 gallon pool rating is based on it running 24/7 set at 100%. That's why its for pools "up to 20,000 gallon".

Always buy the larger cell, it's only about $50 more and will last much longer. It can be set all the way down to 5% if needed or set to run only a couple hours a day.