Growing grass

Im trying to grow grass in a tank but mold keeps growing even though its not too warm ,wet and has enoufg ventilation. Is there something that I maybe could put on top of the grass to kill the mold and not the grass. All advice is appreciated.

Try sunlight...sunlight is a molds worse enemy since its just grass... sunlight would be good for it hahaha why are you growing grass in a tank?

a tank really isnt the kind of place that grass likes to grow in...and even though it might see fine, tanks can get warm and have moisture...causing mould...even if you put it in the sun..the sun will reflect off the glass, making the tank warm, causing moisture and mould...if you what grass grow it in something else, it cant survive in a tank!

grass? or "GRASS"?