Corals looking PO'd when white lights go off.

[Katepete722]

Greetings reef gurus,

I'm looking for some input as I can't find any threads with my particular issue. I have a 29 biocube mixed reef (LPS and zoa dominant) that's been running for 9 months. The previous owner did a LED retrofit upgrade for the hood which includes both white and blue LEDs on separate channels. The blue LEDs are dimmable but the whites are not. There's also no ramp up or down option. The blue lights run from 9:30 am to 8 pm. And the whites run from 10 am to 5 pm.

My problem is this: every morning when lights come on the coral wake up looking rather stressed and shrunken then gradually inflate throughout the day , usually looking fully inflated and happy by about 1-2 pm. Then the instant the white lights go off leaving just the blues, the corals get ticked again. It's pretty stark. The acans, favia, and candy canes will deflate over the course of about 5 minutes. They remain shrunken throughout the night. My euphylias also shrink, though I understand this is normal.

Now I definitely have (and have had) some water quality issues. Namely I was using an expired test kit that told me my nitrates were under 1 ppm, and when I finally got a new salifert kit I found out they're at 50. Whoops. So they are down to 10 now, and I have made some major changes in feeding and water change schedule as well as bringing a skimmer online. But the coral's issue with the light cycle predates (I think) my nitrate woes.

My alkalinity varies daily by about .2. Usually at 8.0 before lights go on and 8.2 at the end of the photoperiod. I drip kalk from my ATO overnight and run my ATS on a reverse light cycle. PH is 8 and doesn't seem to move much overnight.

I'm thinking about getting a new LED unit on Black Friday and going hoodless. Figured I should perhaps figure out what the heck is going on before I drop big bucks trying to fix it. Thanks for any input!!

 

[flooddc]

You can change the light cycle (timer) of the white channel to match the blue channel.
I personal don't like all blue look, so my setting is usually has both channels working together.
typically, with only blue channel on, coral should not shrink (i.e., go to sleep). I am thinking, maybe your blue channel intensity is not high enough. Try set it higher to see how your corals response.

 

[Instigate]

It's perfectly normal for corals to deflate and close up at night. Any pictures of your "PO'd" corals?

 

[Sailingeric]

Like you, they enjoy their sleepy time.

 

[Katepete722]

Hmm, I thought that many of them stayed inflated and extended feeding tentacles at night. Is that further into the night time cycle? I know that my hammers and frogspawn should shrink though.

 

[Instigate]

Hmm, I thought that many of them stayed inflated and extended feeding tentacles at night. Is that further into the night time cycle? I know that my hammers and frogspawn should shrink though.

I notice deflation in all of my corals nightly. And usually late late at night I'll see tentacles on the favias, acans, sometimes trachy. But sometimes they come out earlier. I wouldn't worry about it.