So, if they ate the Nitrates, shouldn't I need it at least about 10ppm? And as for the Cardinals I think I've had them longer than 2 weeks.. As of right now, my stock list is. 3 Nerite Snails, 4 Otos, 6 Glowlight Tetras, 3(was 6) cardinal Tetras, 6(was 7) Lemon Tetras, I also had 2 Black Veil Angels(baby) but 1 died, I think cause it got picked on by the other or because the bag the guy put it in leaked & fell through the paper bag he gave me, & hit my hardwood floor.. I'm not sure what its cause of death was? Anywho.. That's my stock list.. As for plants, I have 3 swords, a banana plant, some guppy grass, some dwarf sag, anubias, wisteria, & some kind of floating plants..