Thanks so much for reply! Main tank is 25 gallons (5 lemon tetras, 3 phantom tetras, 1 cory cat, 1 pleco). She is now alone in 10 gal hospital tank, ammonia 0, nitrite 0, nitrate 10. pH 7.4 (this seems to be where it settles no matter what I do), stats are close to same on main tank. Using API...