I'm looking to replace my cartridge filter with sand for several reasons. As you can see our pool is approximately 23,500 gallons and we have a 1hp pump. Is there a rule of thumb on size of filter v. pool? I was planning on getting the Hayward 24" top mount which is on amazon for about $300. Would it be worth it go with the 27" for $100 more? From what I've read from my searches on here it appears that the only benefit to a larger filter is less frequent backwashing. Is there any other reason to go with the larger filter?