Carpet Plants
I would personally not recommend using java moss as carpeting since they grow vertically more in low-light conditions, with strands clumping tightly together. It would be incredibly hard to tame it to the ground and a nightmare to clean since they're generally messy to work with. They seem best when allowed to grow rampant on bogwood or other ornamental pieces.
Highly recommended by users are having high-intensity light, CO2 injections, and fertilizer tabs/nutrient substrate that is heavy in potassium for the luscious green coloring. The CO2 injections should be checked for proper circulation throughout the tank and not either changing the pH levels to uninhabitable levels, where osmoregulation is disrupted or suffocation occurs for other aquatic life present. They're apparently easy to dislodge initially, while they're still taking root in the substrate, so it may be best to not have the aquarium completely filled yet, to encourage growth with smaller dilutions of the CO2 injections, and not have the filter turned on until there's sufficient growth observed.
