Best Biopellets/Media for Nitrate Control?

[Drew1600]

Have tried Seachem's Denitrate with no results. Should I try Dr. Tims? Sulfur? Any other suggestions? 25ppm nitrate on 29g + 20g sump. The problem is my well water, setting up a DI filter to remove initial nitrate. Just need tips on maintaining there after. Thank you so much!!

 

[Drew1600]

I should add, I live with my parents who will not allow me to hard plumb an R/O system. Figured a canister of DI Resin would be my best bet for initial removal.