We're getting ready to sign a contract this week and I'm having second thoughts about my filter. As of now, we're getting a PLM 300 cartridge filter for our 15x30 uncaged pool. I know TFP recommends the biggest filter you can get. What is the next size up from the PLM 300? I'm wondering if it's worth the cost. We're handy people and we don't mind cleaning and upkeep. I'm going to price these out and see if it's worth discussing with the builder. Thank you.