Bta ??

[davidsea]

Every day late afternoon my BTA will completly close up . The two clown fish will then rub up against it till it opens back up ,an hour or two later.BTA never moves ,it likes it spot in the tank.
10gal nano
18" 300 series Acan LED light
skimmer
Power Head for cir.
Chemi -Pure Elite
Seachem Purgen
sal. 1.024
PH. 8.3
Temp.76-78
NO3-.5
WC -5gal every 2 weeks
Anyone know why ? or has the same going on.