First off you better check into any requirement to were the pool is about a public pool. Most times the filter is downrated for public pools because they want a high turn over rate of water.
Look at this chart from Hayward
http://www.haywardnet.com/inground/product...fm?ProductID=92
looking at the first model in the chart it can turn over 15,360 gallons in 8 hours for a public pool and 40,320 for a residential pool. That is a rating they give just because of the presumed higher bather load in a public pool even if it is the same filter.
I know were I live a public pool must be turned over every 8 hours. I take care of a 15,000 gallon public pool and it has a sand filter rated at 47,000 gallon in 8 hours.
I know the owner will not want spend any more money but a bigger filter is probably needed and change to a sand filter. All the public pools here use sand. Here is link to what I would install
http://www.haywardnet.com/inground/product...fm?ProductID=28. the s360sx model.
I appreciate that extra info. The 8 hour turnover rate for this cartridge system is 12,000 gals in 8 hours. That seems a bit inefficient to me for a 45,000 gal. capacity pool. That filter system model I promised to add info about is available to me now. It's a Clean and Clear Model #160317. There's nothing in the manual I have with it that refers to limitations based on liquid capacity. That seems unusual to me. The only thing I see that relates to what the filter can handle is which cartridge element handles in "square footage of filtered area" it only has listings of elements for 50 sq ft. to 200 sq. ft. I don't know if there's some different formula that calculates "square footage of filtered area" but that makes no sense at all to me. Being pretty much ignorant on this subject, I would just figure that if you have any piece of equipment like this, it would tell you what the filter will efficiently handle in cubic capacity, not square footage. As far as gallons per hour passing through the filter, it seems logical that you've got to be able to filter X gallons per hour over a particular time period. I mean the filter should be able to clean the water with this maximum amount flowing through. You obviously have to filter the entire volume in a time frame that will keep any crap from multiplying in your pool at a rate faster than the pool can filter it out. Anyway, you see my problem perhaps a bit more. I have also told the owner that I would recommend that he just get rid of the cartridge filter and go to a sand filter or even, back to a DE filter. After all, before they put in a cartridge system, they had a DE system and didn't have nearly the problems we have now. Those problems didn't begin until after the cartridge system was put in. I'm just trying to make what I have work, since the owner doesn't seem to be ready to come off the bucks to change out the filtration system again. Any other comments/assistance would be greatly appreciated. I'll also look into that sand filter but I'm sure cost is certainly a factor.