SWCG size?

We are going to buy a SWCG for our in-ground Pebbletec pool in Phoenix, AZ. Our pool is just shy of 12K gallons. We are looking at the 25 K Hayward AquaRite/Swimpure. The dude at the pool store told my husband, "Everyone in AZ buys a 40,000 gallon size even if their pool is only 9,000 gallons because the cell will last longer." I read on Pool Forum that if you have a SWCG larger than 3 times the size of your pool, it may be hard to dial it down low enough.

What do you all think? I don't mind spending the extra money, but I figured I shouldn't believe ANYTHING the pool store guys say without checking here.

Thanks!
Tabitha

Getting something sized 2-3x the pool size makes sense. Anything much more than 3x could have issues with setting the on-time percentage low enough, especially if your pool isn't in full sun or you get a lot of cloudy days in the spring/fall. You can certainly check the specific model to see if they let you dial down to 1%, but if they only have 10% increments, then that might not be good enough, especially if you run your pump for a long time (say, with a 2-speed or variable speed pump that runs at a low speed but for a long time).

I've got the aqua rite system and use the 40k cell in a 12k gallon pool. Works well, I don't have problems turning it down here in FL. My pool gets pretty much full sun, though.

Keep in mind too, that you have excessive heat in Phoenix, which will create additional chlorine demands. There's merit in suggesting to upsize your system. You will have the extra capacity, if needed, and longer cell life.

The AutoPilot offers the ability to adjust the Cell Power output, in addition to adjusting the Purifier % setting, so that you can control overchlorination conditions. That is, with our maximum gallon rated cell, which is based on the highest of 3 different Cell Power outputs from the Digital control unit, we offer the ability to derate it. Going with the largest cell, RC-52 (52K gallons) but set on Cell Power 1 (5 amps) instead of Cell Power 3, (8 amps), you can decrease the amount of chlorine generated, then fine tuning it to maintain your desired level by adjusting the Purifier % setting.

But then again, I'm sure there are many Aquarite systems with the larger cell on smaller pools, to know that the combination works in Phoenix.

You'll love your salt chlorine generated pool!

I'm kicking around some of the same issues. A couple things to remember or ponder. What's your pump run time? The SWCG will only produce when the pump is running. There always has to be water flow. I believe the daily output is based up 24 hour operation. If you're running only 8 hours I think you'd want to get one 3 times the size of your pool for the worst case scenario. That may be overkill but then you can always fine tune it down. Also the cell is rated to produce only so much chlorine in it's life time. (If you go larger and scale production down theoretically it should physically last longer compared to a lower rated unit).
Those much more knowledgeable than me will correct me if I'm wrong.