CX Horticulture Tanlin(formerly CX Nilnat ) is a biological treatment for fungus gnat (Scariad Fly). It is non toxic, safe to humans, animals and the environment. There is no withholding period and it can be used right up to harvest. NilNat is effective in all types of hydroponic systems as well as in soil, compost and coco fibre. It is has an extremely high dilution rate giving the grower a product that can also be used as a preventative measure against these troublesome pests without it breaking the bank! Tanlin is added to your nutrient solution and gets to work at the source of the problem by killing the larvae that are laid by the adult flies around the roots of the plant. It is these larvae that do the damage to your plants by eating away at the roots. Tanlin works by depositing a small crystal by the roots of the plant that the larvae eat. This crystal then swells inside of the larvae causing it to burst and die. You will notice that after a period of time the number of flies in the grow room will start to diminish as the larva are being wiped out. Even though Tanlin will effectively deal will infestations of fungus gnats, don't wait until you get a breakout before using it. Using a few drops of Tanlin in your nutrient solution as a preventative will guarantee that these pests will leave your plants well alone. The 20ml bottle is enough to treat 2000 litres of nutrient solution.