My Duncan's keep closing for several days. I started with 6 heads and now have 12 . They're not huge but seem healthy most of the time. Any idea why they are closing up like this?
1300 is bestMag is about 1400
They are actually on a rock several inches above the sand my parameters are what you said except the mag is a little high.These are fairly easy coral. First thing I see is location. On the sand does not do well as PAR is lower but mainly is that they get irritated easily if sand reaches them. I would elevate a little assuring it gets moderate light and water flow.
Additionally:
Temp 77-79
ph 8.1-8.3
salinity 1.025
nitrate < .04
Phosphate < .04
alk 8-9
Mag 1300
CA 440
any little bugs on them upon inspection? Mine are super happy always and each head larger than a silver dollarThey are actually on a rock several inches above the sand my parameters are what you said except the mag is a little high.