Assuming you are talking about Monosolenium tenerum, it's a relatively easy plant to grow. You just drop it and it will sink to the bottom. I like it more than Riccia as it doesn't come off and float to the surface. The shape of Mono is also very plastic; under bright light it will form smaller leaves(thallus?) while under less bright light the leaves are bigger. A very nice plant, especially for creating bush effect.