photoperiod

I've had two community tanks with tetras, gouramis and catfish for almost a year now, and there really isn't any indication that there's a problem, but try as I might I can't help but feel like I'm doing something wrong when it comes to lighting. So just for my peace of mind, here's a timeline...

Initially I thought that siestas were supposed to be good for CO2 absorption in non-injected setups so I had my lights off for a couple of hours after lunch.   Now I've read that siestas favour algae and aren't a good idea.  Also plants don't recognise a photoperiod in chunks of less than 4...