My best Java Moss growing method so far is high humidity & low, indirect light. Java Moss is kind of a wierd plant. It grows & spreads faster when you suspend it above the water line (or use a seperate terrarium-type setup) in high humidity, but makes longer strand-leaf-thingies & gets fuller underwater. It will still take a month or so to attach itself & cover a coconut shell in the terrarium, but it will take muuuuch longer if you try to do it underwater. Use fishing line to attach some Moss to driftwood, a rock, plastic mesh, etc. All you need is a thin layer, but make sure you get some of the rhizome (brown woody underside) attached too. It speeds things up. After that, hang it from the lid of the sump, or turn a glass bowl upside down on a plate (cheap terrarium), or use tupperware & wet paper towels to make a humid box. Then place it in a window that faces North or South (doesn't get direct sun) & keep adding water to keep it moist. Once the Moss is attached & spread enough for you, throw it in a shady spot in the sump & watch the nitrate drop.
You may be right, my sword plants aren't huge, but I also think my sand bottom is part of the problem. They get root tabs, but maybe they arent getting enough nitrate at the roots....
Tiger-Army: I attach my moss to styrofoam balls & mesh, but some does get free. I have plastic mesh screens in between the moss & any filters/pumps to catch floaters without killing the flow. I clean off the screens every few days & collect it in a cup of old tank water. Once I get a decent mound, I build a new ball or floating disc or whatever I need.
EDIT: To both of you, FISHING LINE is your best friend!!! Use plenty of it!
