In my experience, most (not all) bio-cube fixtures use 0.3 to 0.5 watt leds and have very poor PAR levels. If you are keeping fish only or easy corals (zoas, softies and some easy lps) it may be enough. Finding the PAR levels for your brand and model would be very helpful (maybe data is online from the manufacturer?).
Assuming LC1 is mostly white, LC2 is mostly blue and LC3 is just a bit of blue, here is what I'd suggest. Run LC1 at 50% for at least 6 to 8 hours a day. Run LC2 at 75% for 2 to 4 hours longer than the whites with some before the whites come on and some after the whites go off. Do whatever you want with the LC3 channel. If corals do not look healthy or grow over some long period (like a couple of months, then up the levels to 75% on LC1 and 100% on LC2.
The reason to run the blue channel higher is because the algae (zooxanthellae) that live inside the coral use mostly blue spectrum light to do photosynthesis which helps feed the coral. The white is still useful to the coral, but a little goes a long way. Corals need good strong midday type light for roughly 5 to 8 hours. That's how long the zooxanthellae will do photosynthesis before they shut down. Running the lights longer will not do any harm, but it also does very little useful either. It's more about your viewing the tank.
Good luck.
