Birds nest loosing colour

[reefk]

Not sure why my green birdnet is loosing colour and getting black tip in some branch. Parameters are stable, no change in lighting or flow or placement... everything else looks good expect for this guy.

AlK - 8.4
Ca - 460
Mg - 1360
No3 - 10
Po4 - .03

Is this some time of infection? What can I do

 

[cojo8888]

Using led? Mine has similar symptoms due to using kessil led (famous for shadow low coverage) it's between frag and colony size. So... its much smaller area are whitened compare to yours but yea

 

[reefk]

Using led? Mine has similar symptoms due to using kessil led (famous for shadow low coverage) it's between frag and colony size. So... its much smaller area are whitened compare to yours but yea

Yes it's LED and T5...T5 runs for about 6 hrs and LED for 9 hrs...it's been like that for 6 months now and never had this problem.