Where are you finding Gnatrol? Can't find it in Cali. Are you using liquid Gnatrol or granules? I got my hands on an 3/4 empty 2.5 gallon bottle and it's about gone. Would like to find more.
Here's the link to a store in Cali that sells it.
http://www.groworganic.com/item_PBI095_Gnatrol_25_Gallon.html?welcome=T&theses=7767266