I have ran my 29 Gallon Biocube skimmerless since Nov '12. only broke the tank down once after my trip to Disney World because the compact lighting had a short. lost a montipora but all my LPS and Softies did survive.
SO after that I called Corallife and got a replacement. Ended up breaking the tank down,removing the bioballs and put in a fuge in chamber two. Let the tank recycle and added all the corals back. THis was in Aug'13.
Fast forward to now, I have it topless with a Kessil A150W Ocean Blue with some SPS now. No algae issues .
I think my success is because I do a 3-5 gallon water change weekly.
Also I have a 48 gallon (Star Wars Retro )that just reached a year old, I didn't have a skimmer on it as well until about two weeks ago.
This tank has plenty of SPS ,LPS and ZOAS.
Once I added the skimmer my ACANS started to die
I thought it was because something was eating them ,tried to dip em in Iodine ,Coral Rx but I lost one frag and ended up moving the other frag to the Bio Cube.
The skimmer is pulling way too much nutrients out of the water imo ,I might put it on a timer.
I'll try to upload some pics for you to see
I will say ,if I had to do it all over again,I'd purchase a skimmer from the get go.