Split photoperiods - is there a downside?

[jahmic]

I've been running a split photoperiod on my 20L zoa tank...I'm running about 100W of LEDs over the tank (dimmable). My lighting schedule looks like this:

7 am - Blues on
8 am - Whites on
10 am - Whites off
11 am - Blues off

---Dark---

4 pm - Blues on
5 pm - Whites on
7 pm - Whites off
8 pm Blues off


A little background...I decided to do this since my tank is in a room with a very large South-facing window. During the early morning and early evening hours, some sunlight was peaking through the windows and hitting the tank. I will probably hang some blinds soon, but either way, enough light passes through that the zoas tend to "stretch" towards the windows during those hours. The long polyps looked like crap, and they honestly looked unhappy. Although I could just run the lights from 7am - 3pm and essentially solve the problem (at least during the winter with these short days), the lights would be on while I'm at work, and that's just boring, lol.

So far, the tank is looking healthy. The tank isn't completely "dark" during that downtime...although no rays of light are striking the tank through the window and causing my corals to stretch toward the front glass, there's enough ambient light in the room to not interrupt my flameback angel's sleep cycle.

Anybody else have experience with running a split photoperiod? Have you noticed any downsides or improvements upon going back to a regular photoperiod? I'm not getting much nuisance algae growth...just the typical brown/green spotting on my rocks that you'd expect with a new tank...I'm pretty sure my angel snacks on anything else that would become a problem anyway. The corals look happy...and I get to enjoy my tank for a short while in the morning before work, and again when I get home. I'd claim that it'd be beneficial in the summer as well due to shutting the lights down during the hottest part of the day...but since I'm running LEDs about 8 inches from the top of the tank, I doubt that's going to be an issue.

Is there any reason I should be concerned about running this tank's lighting this way?

 

[SAZAMA]

your ph may fluctuate much more with less white IMO

 

[jahmic]

Interesting...that's sort of counter-intuitive to what I expected. I was hoping that, if anything, although the pH would go up and down more frequently during the day, that the levels would be a little bit more stable...in other words I'd expect to have smaller fluctuations since the shorter photoperiod would produce less CO2 in the system.

I have a FW planted system that I used to run a reverse photoperiod on...but my emersed growth (above the waterline) didn't care for it much, so I stopped. That tank is slightly overstocked and relies on fish expiration for CO2 production...the reasoning behind the split photoperiod was that it allowed CO2 levels to build back up mid-day, as opposed to being depleted by the end of a longer photoperiod. My submersed plants definitely benefited from that setup, and I got less algae growth since available CO2 allowed the plants to outcompete nuisance algae for dissolved nutrients in the water.

I might eventually hook up a pH monitor and see if my pH is all over the place due to the split photoperiod.