What works best for creating a "water carpet"?

I would like to find a way to make the bottom of a soil tank lush and green without waiting forever for it to happen or spending a lot of money.

My idea is to use aquarium soil and get everything going and eventually add in shrimp or crabs.

Quote from Chirianti

If you select Dwarf Hairgrass for your tank, you could get a water carpet in no time. It grows very fast and with medium light and temperature. It does require trimming every two weeks.

I will look into this, thanks! Can it be bought as a starting base attached to some so I can just put it in and allow it to spread over the bottom?

Quote from Bloggerbler

You can also try Cuba (Hemianthus callitrichoides) it's one of the smallest aquarium plants in the world. It grows over the bottom of the tank with tiny round leaves, and like most carpeting plants it spreads rapidly when separated and planted in clumps with a grid-like pattern. But should maintain proper water temperature in the range of 64-82 degrees Fahrenheit. Could be a little challenging but you would get fast and stunning results.

I just looked it up...

and this looks amazing! I have a good heater in my tank which keeps the temp between 74 and 78 at all times so that shouldn't be an issue. I did see some tanks have a yellow tint to the plants. Is this what happens when it becomes unhealthy?