Everything turning brown
A few days ago everything in my 20gal took a turn for the worse. They started out growing emersed, but have been growing submerged for at least a month now, and until recently, everything seemed stable. there's a brown dust building up on the tops of leaves (mainly brazilian pennywort). my sword is browning with recently healthy leaves looking translucent, and a variety of stem plants are all browning, with node roots suddenly brown and lifeless. Also of note, my micro sword has started floating to the surface. There's 3x13w 6500k CFLs and two one liter bottles of DIY CO2 on the tank. What's going on here?