First how big a tray?I grow in11/21 inch trays,using 1.5cups of seed.I am averaging 13ozs a tray using barly seed from wheatgra SSKI ts.com.The weather in central ILL. is hot and dry.I grow in growracks with shadecovers,60%.I sprout inside,in the basement set outside when the sprouts are 1.5 inches high.I harvest 4-7 days latter depending on conditions.I water 1 time a day,exept for the day of harvest.I water early and give a good spray of water in the late afternoon,2-4ozs. about 3hrs. before cutting.This increases juicyness!It could be seed or growing medium,or growing issues.Are the blades off colored on the tips?Are you growing in direct sunlight,is mold an issue?Modifying your growing tech. will increase your yield,but it will take a little expieraminting.My first tray was barely over an ounce,very dissapointing.But I did grow some killer mold!!Good luck and happy growing!