Cryptosporidium is a chlorine-resistant protozoan parasite that infects an estimated 823,000 Americans annually. The most common mode of transmission for Cryptosporidium is ingesting contaminated recreational water from treated (chlorinated) aquatic venues. Cryptosporidium oocysts have an approximate diameter of 4.5 microns and easily pass through sand and cartridge filters where the pore sizes in the filter media are typically greater than 50 microns and 30 microns, respectively. A regenerative media filter (RMF), a type of precoat filter using perlite filter media that looks like white powder, was evaluated under a wide range of operating conditions to determine the level of Cryptosporidium removal possible. Cryptosporidium-sized microspheres were used as a surrogate to determine the removal of the RMF connected to a 1500-gallon swim spa. The amount of media added, the grade of filter media, the degree of filter clogging, the steps in the filter regeneration procedure, and the filtration rate were all varied to assess their individual impacts on microsphere removal by a filter that regenerates its media every 24-hours. The RMF baseline removal of microspheres was found to be 99.6% at 1-hour and 97.1% at 24-hours. The experiments performed determined that all the parameters evaluated significantly impacted RMF removal efficiency, but all of those differences were not large or important. Increasing the filter loading rate by 25% from 1.6 gpm/ft^2 to 2.0 gpm/ft^2 decreased microsphere removal at 1-hour from 99.6% to 97.7% and at 24-hours from 97.1% to 91.6%. At a constant 1.6 gpm/ft^2, increasing the amount of perlite filter media by 50% from 7.5 lbs./100ft^2 to 11.25 lbs./100ft^2, increased removals from 99.6% to 99.8% at 1-hour and 97.1% to 98.7% at 24-hours. Overall, RMF’s were much more efficient at removing Cryptosporidium-sized particles than sand and cartridge filters based on values reported in multiple peer-reviewed publications.