http://www.biconet.com/ is where I got my Hypoaspis mites.  They eat the gnats before they sprout wings and exit the soil.  They come in a container with a hole in the lid and you just sprinkle them on top of the soil.  They are mixed in with what looks like saw dust.....the mites are not visible to the naked eye...not mine anyway. 
Some people use them in with their reptile pets....read they work there well too.

I've talked to Eric at Biconet.com twice and he has been very helpful.  He recommends the Hypoaspis mites.  He also said that Gnatrol was a good product too but that is a China product.....so I went with the mites.

Very cool. I may have to try those. Thanks for sharing.

On a related note: Hey TONYSAC, are these what you saw in your bags of sphagnum? Check out the link. You might be luckier than you thought.

Related discussion:
http://figs4funforum.websitetoolbox.com/post/joys-of-fighood-(gnat-and-aftermath)-6107414
(dang... another of those threads with parentheses in the subject/title... that link won't work, but cut-and-paste would).

Mike

Hey John they can very well be them little guys im not 100% cause I cant really see them even under a magnify glass there tiny and fast.

I use these in a commercial greenhouse, we put them around the floor where insects may have gone during winter or between crops.  Pepper growers tend to use these or atheta to control fungus gnats in greenhouses, hypoaspis is much cheaper as well.  I find that the hypoaspis is extremely effective when put in at low pressure or as preventative if you know there are some bugs around before.  

Of course, you could always just get some Bounce fabric softener sheets.
http://hortsci.ashspublications.org/content/45/12/1830.abstract

Mosquito Dunks (BT) in my watering can seem to be winning the war ... so far. I see an occasional adult, but their numbers are dwindling, even as I add more plants. It takes a while to break the cycle.

Thuricide  (made by multiple companies, among them Bonide, Safer, and High Yield) is a liquid that contains already-started colonies of BT (same species as Mosquito Dunks, maybe a different subspecies).  I've used Thuricide (by Bonide) and Mosquito Dunks.  Both worked for me, but using Thuricide was faster.  I think it took longer for the colony to get started using Mosquito Dunks.  But Thuricide was a little messier too  (dealing with liquids rather than solids). 

Mike

<<edit:  In one spot I had misspelled Thuricide... fixed it. >>

I would bet you are correct. It seemed to take a bit for the bacteria from dry dunks to establish, as the cycle of adults, eggs and larvae was broken. Either way, it was far better than breathing in gnats every other day.

Mosquito Dunks are BTI not just BT which some use. The regular BT works somewhat but not that good.

Does anyone know where you can buy the Bounce® original brand fabric softener dryer sheets? I’ve checked the local grocery stores, eBay and Amazon. All they have are these new scents: Outdoor Fresh, Free and Sensitive, Fresh Linen Scent, Febreze Fresh, For Men –Pure Sport, Sweet Dreams.
Has anyone used the new brands with any success at repelling fungus gnats?

http://hortsci.ashspublications.org/content/45/12/1830.abstract

http://hortsci.ashspublications.org/content/45/12/1830.full

Please don't laugh at this newb.   what do you do with the sheets?    By the way   cats hate dryer sheets.    put one where you don't want a cat and they will steer clear of that place.  

I had a gnat problem with my houseplants. I used fabric softener sheets that I got in the dollar store. I cut them into strips and put them on top of the soil in the planters. It worked! Gnats gone!

Thanks Valerie. Perhaps any fabric softener sheets will do, not just the ones in the research. That's a great idea to cut them into strips.
I've only seen a few gnats around my cups so far, but each week there seems to be two or three more.