24/7 here too. Mine pulls more out at night (but my fuge/frag section is lit). As long as you're pulling out the nutrients that would cause algae.... less than 24/7 should work fine. Also remember your skimmer pumps a lot of O2 into the system, be aware of not having a stable amount of O2.
Also, if you haven't already, there was an "Unofficial New User Guide" that was invaluable source for Apex information. I found the Apex really easy to set up with it. Apparently they merged that into the newest guide.
http://reefbuilders.com/2012/10/23/apex-comprehensive-reference-manual/
Newest Neptune manual: http://www.neptunesystems.com/wp-content/uploads/2012/10/Comprehensive-Reference-Manual-v1_0.pdf
You can see my programming here: http://www.reeftronics.net/d-m/apex-program
http://www.reeftronics.net/d-m/apex-status
Also, if you haven't already, there was an "Unofficial New User Guide" that was invaluable source for Apex information. I found the Apex really easy to set up with it. Apparently they merged that into the newest guide.
http://reefbuilders.com/2012/10/23/apex-comprehensive-reference-manual/
Newest Neptune manual: http://www.neptunesystems.com/wp-content/uploads/2012/10/Comprehensive-Reference-Manual-v1_0.pdf
You can see my programming here: http://www.reeftronics.net/d-m/apex-program
http://www.reeftronics.net/d-m/apex-status