Must replace filter - getting differing size recommendations

[johnnyringo]

So my 300lb sand filter split down the side. When questioning various pool companies about a replacement, I am getting a wide variety of sizes being recommended. I think I am going to switch to a cartridge filter due to having to use so much hose to properly backwash because of the design of my property. When talking to several pool companies, I am getting most recommending a 420 or 520 Pentair. The 520 seems huge - do I need that large of a filter.
I have an in ground saltwater pool that is approx 18000 gal. My pump is 1hp.
I must make a decision very soon. Any advice is greatly appreciated.

JR

 

[JasonLion]

Re: Must replace filter - getting differing size recommendat

Welcome to TFP!

You don't have to get a large filter, you could get by with a 150 sqft filter. But if you can afford it, you will be happier with a larger filter in the long run. The larger the filter the longer you can go between cleanings and the more efficiently the filter will filter. We always recommend getting the largest filter you have room for and can afford.

 

[johnnyringo]

Re: Must replace filter - getting differing size recommendat

Thank you for the quick response!

With all things remaining equal, does a larger filter reduce flow? Am I right in assuming that the 420 will still be significantly oversized for my application?

Thanks again!

 

[Voodoo_Pool]

Re: Must replace filter - getting differing size recommendat

Welcome to the Forum!

I think this thread may answer your concern about filter size affecting (or not) flowrate: hydraulics-101-have-you-lost-your-head-t915.html

According to Pentair, the 420 and 520 are both rated the same so getting the bigger filter will allow more time between cleaning.

As Jason stated, bigger is generally better with regards to filter sizing.

Enjoy!

 

[257WbyMag]

Re: Must replace filter - getting differing size recommendat

The 420 should be plenty for a pool your size. It's a great filter by the way.

 

[johnnyringo]

Re: Must replace filter - getting differing size recommendat

Great info! Thanks for the quick and informative replies.

 

[JasonLion]

Re: Must replace filter - getting differing size recommendat

Using a larger filter increases the total flow rate just a little because the larger filter has less total resistance to water flow. More importantly, since the water is spread out over a much larger filter area, the amount of water passing through any given patch of filter fabric is moving much more slowly and that allows the filter to catch finer debris that a smaller filter would catch.

 

[johnnyringo]

Re: Must replace filter - getting differing size recommendat

Awesome. The 420 is being installed today. Thanks again for the great and timely info. It got a little overwhelming with so many pool "professionals" offering different recommendations.

 

[ed0846]

Re: Must replace filter - getting differing size recommendat

Awesome. The 420 is being installed today. Thanks again for the great and timely info. It got a little overwhelming with so many pool "professionals" offering different recommendations.

I installed a 420 this spriing...I love it !!!!