In the other post you mentioned small/nano/pico reefs with no filtration. I have never seen that I guess its like the "natural" freshwater

I'm not sure if were allowed to post links to other forums on here, so I whole heartedly apologize if were not.

But, check out www.reefcentral.com and you'll find more than you need there!

I like pico and nano reef tanks myself. I currently have a 2 gal Pico, a 3 quart pico, a 16 gal Nano and some larger tanks, all setup as reef with fish.Pico tanks are easy keepers but still require monitoring, and the first couple of months or weeks may get you to the point of wanting to throw it out thew window......Smaller containers are much less forgiving in what you can and can't get away with.....Temperature swings are easy, and cooling or controlling your tanks temp and proviinding the right amount of light can giv eyou fits, but its all readily workable to solve if given some time and tinkering....

A small tank like a 2.5 gal with a good 1" or so of good live sand and the required live rock stocked at the rate of 1.5 pounds per gallon is a good start.....so you would need as a minimum roughly 4 or so pounds of fully cured live rock.......Sinc eyo have such a small tank its nice to have a hang on back (HOB) filter.......and most any hob filter with a large filter media chamber will do, preferably with an adjustable outflow. The most commonly used hob filters are made by Aqua Clear......They have adjustable water flow, and nice large for their size filter media chambers....Add a baffle between the pump inflow chamber and the media chamber, so the water thats is being pulled into the pumps chamber has to flow up and over the baffle into the main filter media chamber......In the filter media chamber add a small amount of live sand or miracle mud, and some small pieces of fully cured live rock rubble, and some macro algae.......you may have to put a screen or some such item on the outflow spillway to keep macro algae in the filter media chamber, which has now become a refugium chamber.......Top off fuge with a decent PC type light, and have decent lights on the tank itself, and your ready.....once cycled, add your critters.....A 2 gal with proper water flow and filtraton, can support a small species of nbano fish, like a blue neon goby easily. The live rock and live sand are your filtering media.........but you can add a single fiber or sponge pad to collect larger junk, but do not ad any other filter media as it tends to become a nitrate factory......The LR/LS will remove and utilize the nitrates produces as well as the fuge.......With as fish in it, a 10 to 20% water change every week or so is fine, or without a fish, I do a 50% or more water change once every two or three weeks......
I also use a small hood with power copmpact florescent lights with a muffin type cooling fan to keep things cool, and my picos all run a pretty constant 79.6 to 80.1 deg temperature.......Assemblying the tank and filter/fuge and lights is the cheap end, its what you spend $$$$ on stocking them thats expensive. I have one pico with quite a few dollars worth of very colorfull inverts in it and with a lunar night light its just awesome.......not that it looks bad during daylight but at night with all the florescent inverts its mind boggling........

I have been tempted to try a nano. I currently have a 46 gallon. Here is another good web site, www.nano-reef.com

Reefcentral.com is also great, as bheron suggested.