I bought some Java moss and tried everything I could to attach it to something. It ruined my filter and tied up everything else in the tank with it's wandering strands. I took it out and flushed it eventually, I've been much happier with my other plants
I just have one recommendation regarding Java moss, something I wish I thought of myself before putting it in my small planted tank. If you buy a bundled clump from a store, be sure to unbundle it, and soak it for a while in a container of tank water, separate from your actual tank; then shake it thoroughly before planting in your tank. When I put my moss in my tank, it quickly clouded the water with sediment, which took my sponge filter a week to clear up (fortunately I didn't yet have any fish in the tank at the time)! The one benefit from this experience is that it cultured my tank with a great diversity of infusoria (daphnia, rotifers, planaria, etc.), which my fish have had great fun hunting down! I'm just keeping my fingers crossed with the hope that no parasites were in the mix.
I bought some Java Moss about a month ago and I find it quite slow growing under low lighting. I was expecting some fry from my guppies, so I wrapped fine netting around the filter so that the fry won't get sucked up. I didn't realize by wrapping the netting around the filter, I also prevent loose Java Moss from damaging the filter.
I purchased a ball of Java Moss inspired by others' comments. First it was growing very slowly, but in three months it took over the entire tank. It killed almost all other plants! Besides the fact that this moss covered the entire bottom, it also grew on large leaf plants, completely blocking them from the light. It was a real plant killer! The only plant that survived the invasion was a fern. I had to clean my tank every 3-4 days from the moss and remainders of dead plants. Ultimately I had to dry up the tank.
Java Moss (Vesicularia dubyana) is a wonderful, easy-to-care-for addition to any tank, primarily planted or not. I bought about a fist-sized clump about a year ago from my LFS. The guy said it would do fine in any light and water. The water part of his description was right but the light wasn't. I found it grows slowly under high or clear light, but it grows quickly and heavily under low or yellow light. It's my favorite plant. But be careful, it grows VERY quickly under low light, so prune very often! I have about a football-sized clump now, quickly growing.
I bought a small bag of Java moss a few weeks back. It was pretty expensive but I decided to give it a try. I had no place for it in the tank, so I left the bag floating in the tank more than a week. Then I realized that it was dying, So what I did was took all the fishes out, got 3 pieces of driftwood and held the Java moss in place on the driftwoods with the help of a net. On one driftwood I held Java moss in place with thread. I supplied the tank CO2 with DIY CO2 injection system. The tank is 100 liters where I have a 20 W Fishe light tube. It's been a week now and I can see fresh green Java moss coming out from the net. When I started this 80% of the Java moss I had was dead.