Reduced Light Cycle - How much?

[JeF4y]

I'm looking at reducing my light cycle to aid in my algae war. Currently battling a small outbreak of Bryopsis and a massive outbreak of Gelidium.

I have an 8 bulb ATI fixture which has 2 modes, 1 mode (sunrise/sunset) lights 2 bulbs and the other adds the other 6. The bulbs are only around 5 months old (if not less) and are a mix of mostly Blue +, a white actinic, a fiji purple and a 10,000k daylight.

Right now I'm running all lights for about 9 hrs, and running the sunrise / sunset 1 hr before and 1 hr after all lights kick on. So the total light cycle is 11 hours.

My corals are a mix of mostly LPS & softies with 1 SPS (birdsnest).

I can't really find anything about how long the light cycle should be or should be reduced by.

Thoughts?

[theyammieguy]

Some people go lights out for 2 or 3 days.

[JeF4y]

Right, I understand the total blackout concept, but hear so much about 'reducing the light cycle', but it's not generally quantified by how much.

[DThompson]

Natural reefs for the most part only ever get a few hours of direct light per day. You could give around 4 hours of direct light and the sunrise / sunset mode maybe 2 hours before and after the brightest period.

As far as your Bryopsis is concerned, what is your Mag level. I have been very successful at killing it by raising my mag level above 1300.

[JeF4y]

My MG level is just under 1300 right now. I've read a lot about using the Kent Tech M to kill bryopsis and may end up there, but I'd rather not induce chemical warfare right off the bat.

Thanks for the tips on the lighting.