Hi, I have a Red Dragon Flowerhorn fish. We had him in a 30 gallon tank and of course he got bigger, so we upgraded to a 75. We didn't have a gnat problem in the 30, but they are going crazy in the 75. I do water changes about every 3 weeks. Any sugesstions on how to keep these gnats out of his tank??? I completly remove them all when I clean it, and a few days later they are back. Do you think his light would help? I keep it off most of the time because he hides out in his cave when it's on, he likes the dark! Thanks for any advise.

I would suggest having strong water surface agitation and sealing the top of the tank. That should do the trick. Good luck!

get a power head direct the flow off your one of your side walls to deflect current