Appropriate Blackout Length/Time period

[Nanoreefboi]

So I’m battling some green hair algae, and it’s on its last legs(finally!). The big turning point in the fight was when I added a refugium to directly outcompete the GHA of nutrients. Now I have decided to do a main tank blackout while running the fuge light 24/7 to weaken it more, and I have one main question:

How long can I have the main tank without light for before I start to have negative effects on the coral colonies?

Any input would be helpful, thanks for reading.

 

[JCTReefer]

3 days is pretty safe. I’ve done a few blackouts for 3 days with zero issues. Just make sure when you turn the lights back on to light acclimate your corals back to your previous intensity/par levels over a few days.

 

[Nanoreefboi]

3 days is pretty safe. I’ve done a few blackouts for 3 days with zero issues. Just make sure when you turn the lights back on to light acclimate your corals back to your previous intensity/par levels over a few days.

Ok thanks for you help!

 

[rogersb]

3 days is good. I don't worry about acclimating coral back to light. Storms last days and then it's full sun again.

 

[JCTReefer]

3 days is good. I don't worry about acclimating coral back to light. Storms last days and then it's full sun again.

Honestly, on the first two blackouts I didn’t acclimate anything light wise. Went straight back to my previous schedule. Corals never missed a beat.
Last blackout I did. About 1/2 intensity. I couldn’t tell a difference either way. I just keep LPS and softies though. Not sure if it would matter with more finicky corals. But yep, they deal with storms in the wild all the time. And right back to full sunshine. I think corals are more resilient than we give them credit for.