QUOTE(shaggydoo541 @ Aug 17 2007, 03:31 PM)

So I guess my reef isn't real since I don't have a skimmer. In that case I should probably report my 'fake' reef growth to some kind of scientific journal since I am seeing great expansion in many 'fake' pieces of coral

I've got a 120 and kept an 18g very successfully with no skimmer. Skimmers are on a lot of phenomenal tanks but from my experience they are FAR from necessary and in my twisted view

they are harmful in that I imagine they are removing beneficial particles. Others imagine they remove waste. Either view is opinion only and so use your own judgement here.
I think it is absurd to say that just about anything is 100% in this hobby. I think the only 100% reality in this hobby is that we need to keep the water salty... although to what degree can even be debated. Keep an open mind and realize there are lots of ways to keep a healthy reef tank.
Skimmers, by design, remove waste. Whether or not they also remove anything beneficial is what cannot be proven. One thing is for sure though, nothing that a skimmer removes is necessary to keep a successful reef tank, as the huge majority of tanks use them and not one of them has crashed because of it (with the exception of Steve Weast's, but that was a combination of factors).
Nanos can
definitely be run without a skimmer. But, as I've already said, using a skimmer will help counteract many newbie mistakes, ie overfeeding, adding chemicals that shouldn't be there, dead fish, poor oxygenation, etc etc.
Now, as for ATOs, the only time you hear of a horror story involving ATOs it is
always due to poor planning or human stupidity. Any decent ATO will never fail, but thats not where these horror stories come from. What happens in those stories is that the ATO pumps too much fresh water into the tank and lowers the salinity too fast. Now, with proper cleaning, this should never happen on its own. It usually happens if:
1) The reefer does a water change and forgets to turn it off - Stupidity, check.
2) The reefer has automated too many things on his/her tank and hasn't thought through all of the potential failures - Stupidy, check. Poor planning, check.
3) The reefer changes some aspect of his/her setup without thinking through its potential consequences with the rest of the sytem. - Stupidity, check. Poor planning, check.
Now, what are the benefits of using an ATO? Constant salinity, less maintenance (constantly topping off), more automation.