nope i haven't done the sand yet .... you know what??? I haven't done anything besides sticky traps and using the tanglefoot from the sticky traps at the rims of the pots ... i even went as far as to smear that sticky shit on my floor. now i have gnat lined planters. I'm thinking i'll do an organic mix ... it seemed to help the last time. My hydro guy kinda discouraged me out of any solutions. When i asked what he would suggest for gnats he said " well you have a better chance getting rid of mites than you do gnats" ... then went on to try and sell me some gnatrol and foggers .. my space isn't that big and the gnats weren't that bad at the time.
I've had the problem before and simple steps helped it out ....just vacuuming the tent everyday and some kung fu helped with them the last time. I'll get it under control but at this point i would say it's not a mild problem any more with these things ... I'd say moderate. another thing
I've been told gnats just pests more than anything and do not affect much if anything during the grow. I've also read how they fuck up yield and vitality to plants .... I'm not sure. I just know that i'm not really interested in giving my plants a soil drench of bt a month into flower. 3 weeks technically. so sand will be coming ... hot pepper, garlic, and tobacco topsoil spray is also looking to be the route