200,000 gallon commercial pool filter sizing

[Matt Ush]

Hey guys,
I'm working with limited space in the equipment room but if I did my calculations correctly, a pool of this size needs to turn over about 550-600 gallons every minute to achieve a 6 hour turnover ratio. The pool is a salt pool so we selected the Pentair 15HP EQ Series for the pump but were having trouble finding a set of filters that can handle this amount of water. I notice a lot of pools we visit just throw a few Pentair Tritons in there but when I did the math, its very undersized. I'm looking between the Astral 71" sand filter (dual setup) and the Pentair THS Series which only has a turnover rate of 400 GPM. Do I really need filters of this magnitude or am I calculating wrong? If I choose the 2 Astrals, they will not fit in the room.

The system is all 4" pipe btw.

 

[Bama Rambler]

Does the AHJ require you to meet the recommended turnover rates? If they do then you have no choice.

Would the Astral 79" fit? The 79" is good for over 600 gpm.

 

[Matt Ush]

They actually currently meet the correct turnover rate based on math so I'd like to keep it the same, but I don't believe it is working the way it should. They have 6 residential D.E. filters inline, all with 2" plumbing as their filtration. As you go farther down the line, the pressure drops from 30 to 3 PSI. The first filter is overloaded and the last one is barely doing a thing.

I'm looking at the catalog and it appears the 79" would only meet those specs with 6" plumbing. All the plumbing at this facility is 4". I have about 7' by 4' of space to fit the new filter. The room is very undersized for how large the pool is imo.

 

[Bama Rambler]

Are the existing filters headered off the 4" pipes?

 

[Matt Ush]

Yes, they each reduce to 2".

 

[Bama Rambler]

If they're plumbed manifold style like they should be and the pump is capable of providing the proper flow into the plumbing, there shouldn't be a lot of pressure difference between the first and last filter.