Sponge for reducing Nitrate?

[PheonixKingZ]

I have no clue what “capsule” you speak of. Picture?

 

[Tttay89]

I don't have a picture as they have now been dissolved and eaten. But they kind of looked like these ones. The fish all seem fine. They may have even spat them out but I'm sure I didn't see any coming back out their mouths.