How does one determine the right size cartridge filter?

[politeoffice]

As I am currently SLAMing my pool dealing with an algae outbreak I am wondering whether the cartridge filter that was previously installed for the pool is the proper size. My pool's roughly 12k gallons and the current filter is a PA90, so I guess that means it's a 90sq ft area for filtration.

That seems rather low to me and I found myself needing to clean it weekly to keep the PSI down when the VSP is running at higher RPMs (such as on startup). Circupool recommends not having the SWG active when PSI is over 20, IIRC.

I looked in Pool School but didn't see any recommendations on the topic - is there a rule of thumb I can use other than "bigger is better"?

 

[jblizzle]

There is a chart around somewhere that I use to provide recommendations.

For your pool size and season length, I would suggest a minimum of 180sqft ... so double what you currently have. And of course ... "bigger is better"

With a 180sqft and assuming you maintain the chemistry and avoid algae, you should only need to clean it a couple times a year.

 

[RedBluePool]

Pentair clean clear plus 420 is good for 20 and under. With your 1.5 hp pump and 12 pool, I think that would be ideal.