*4 hours is not very long for the plants to produce food. And the natural light during the day, is it direct? Without direct or moderately direct sun the plants have no way of producing food. The salvinia I experimentally put in the kitchen window does not receive enough light - though it is natural- and I always find dead leaves.
-During the day the blinds are slightly turned up and there is a sheer curtain. so it is more indirect light i guess. I will open up the blinds and pull the curtain until I get a better tank light.
*The glass beads are holding down the rhizome?? Take it out. You can attach the roots (the stringy bits) to a piece of wood or something to hold it down. I bought a dollarstore weighted fish plant, removed all the leaves and tied my anubias to the weight base. The glass beads are otherwise fine- though I don't know for how long with the sword plants you have.
-OK. I will unbury it and see how I can keep it weighted down. I don't have any decorations in the tank except for the beads, plants and a floating betta log. New idea. I may try and use the base of the old fake plants that came with the tank.