I don't know what I am doing wrong but I can never get my floaters to grow at all. I tried frogbit twice and now my water lettuce is slowly melting. I don't know what to do or what I am doing wrong can someone give me some advice? They are in my 20 gallon long, SA tank with water temp at 82 degrees, light is a Aqueon T5 dual light fixture with a 6,700k bulb and a colormax bulb, light is about 7-8 inches from water surface, sponge filter and sand for substrate (no plants). I have 5 Apisto Cacatuoides and 5 black neon tetras. Anyone have any clue as to why the water lettuce keeps melting? Not enough fish waste, too much water agitation, too much light wattage? I'm lost please help.