The omega line is quality but not nearly as efficient as the wheateena workhorse models from sundance.I personally own a greenstar2000 but tend to mainly use my vita-prep-3 along with a nut-milk bag to juice grass with.As far as growing medium goes it depends on conditions I use 12 cups of compost and 4-6 cups of vermiculite.The vermiculite holds onto water well and this is good in high heat and above ground exsposier in the growracks.Greenhouse growers generally use perlite in there controlled enviorment this works well.The key is moist but never WET.I grew allot of mold during the first month do to lack of a green thumb.It takes trial and error to get to the place where you know what works and what doesnt.Once I place the seed on the growing medium which is moist but not WET I dont water directly until the grass is 3-4 inches tall.At this point I will take the flat outside and water well if theres no rain in the imediate forecast and the humidity isnt to high.Mother nature dictates your actions in the great outdoors and yields go up and down depending on these variables.The only way to deal with mold is strict moisture control which prevents the mold from taking over the flat.Watering from the bottom up can be helpful if mold becomes a issue.Just make sure you dont over water the grass this is the biggest problem of all.May your grass grow tall and your yields be plentiful.Jeff.