Nitrate issue

Hi, so my tank cycle has now completed, 0ppm ammonia, 0ppm nitrite but my problem is the nitrate, it is at 25ppm, I can?t seem to get it to lower I have done multiple water changes with no change. I am using NSW and tested the water at 2ppm nitrate, and using RO/DI top up. What should I do ? Should I get a nitrate remover ect, I can?t get my hands on any sort of Cheeto ect atm so please help ! It?s so frustrating, as I have been so patient. Also it will be a Fowlr tank for awhile so won?t be in any rush for corals, but what nitrate ppm will fish be able to handle ? Thanks