5) PLEATCO PWK30 Pool/Spa Replacement Filter Cartridge C-6430 Watkins Hot Spring
This is a premium Pleatco PWK30 Filter Cartridge.  The Pleatco PWK30 has a longer life, uses less energy, makes cleaner water and uses a free flow technology which is 20% more efficient.  Not drilled PVC which causes less wear and tear on pump.