Has anyone used Gnatrol?

I was wondering if anyone has used it, is so how well does it work and how long does it take. Can fungus gnats cause any problems

Yes, the fungus gnat larvae that are living in the medium are the problem, they feed on the roots. If you use Gnatrol, it will kill them. You should mix a batch of Gnatrol solution, and feed your plants with it, then add nutrients to the solution and continue feeding for a week. Repeat that twice, and you're finished, and so are the gnats.

HTH

Thankyou so much potroast. Since i have an aeroponics, should i just put the solution in the reservoir, and spray my rockwool and hydroton. If so how much would i mix with 13 gallons of water

What you need to do is follow the instructions on the label of whatever product you have. Dosage amounts depend on the concentration of Gnatrol that you buy, and the store clerk can answer specific questions.

HTH