waterchages

Hi all, was wondering if anyone could share any tips on how they remove phosphates from their evo’s? I’m currently sitting at 0.21ppm! I’m running a table spoon of rowaphos in chamber 1 and doing 10% weekly water changes with ro/di water from my lfs which tested 0.02ppm for phosphate...

I had a random thought, Does anyone know in aquarium's like Sea world and other big aquariums, how often do they do water changes on their massive tanks?