Xenia closing after lights off

[das75]

About 1/2 hour after MH turns off some of my Xenia closes up tight. The Xenia is two types all originating from four cuttings. Some times just one type close, other time both types and not always the same pieces. About 1/2 hours later they all open back up.

Probably something with pH as see slight dip, using Salifert test kit so guessing, but normally 8.2-8.3 and does drop maybe 8.1 when I test 1/2 hour after lights off.

Thinking reverse lighting on sump with macro (currently not lite and only a bit of halimeda in tank to move over) but wondering if there's anything else I can do as really don't want more lights and how stressful anyway?

Tank has been up since spring but this is something that's started about a month ago.

Tank is 145g, 75g sump (run about 1/2 volume), lots of Xenia with a mix of some SPS and LPS, and crocea. Lights 2-40W on 12.5 hours with 2-250W MH on for 8 hours in between.

 

[dnorton1978]

This may be a dumb response, but my xenia have always done that at night. In the morning when the light start to come back on they open back up like normal.

So, to me this seems to be a normal thing for the xenia, IMO.

 

[Anonymous]

Yeah, that's just what xenia do at night.

 

[das75]

What has me concerned is this is something that has started fairly recently, they don't all do it, then the ones that do, open fully back up after about 1/2 hour.

I have a frogspawn that retracts during the night, that I can understand it's just with the xenia it's random, other than the time. One night one area, other night, different area and the amount can vary from a few stalks to 1/2 the tank.

 

[SnowManSnow]

its normal
you close YOUR eyes at night too