I am currently battling these dratted things. Having bioactive enclosures makes them an almost constant problem. I have Katchy’s which do a great but incomplete job. Carnivorous plants can help, specifically drosera capensis. Currently I’m hatching out praying mantis ooths, which will take care of the flies and then your chameleon will take care of the mantids. All of these will take care of the adult gnats, but not their larvae. As a back up and final resort, I have Mosquito Bits. I am not sure if it will kill of my clean up crew, so I am hesitating using it in my enclosures. I have used it in my back up potted plants and had an almost immediate reduction in flying pests. It is supposed to kill only mosquitos and soil gnats and not beneficial insects.