[anthias]

good morning ,
today after half an hour of switching the tank lights on ,I note somthing like dust coming from some area in my tank, then I followup the source it was coming from the macro alge it seems like it was burning and changing color and at last became translucent as you can see in th pic with the red arrow,it was in one branch only of the alge,and also you can see in the same picture the blue arrow that another typ pf alge changed from green to brown color(this one happend slowly it takes days to change color)
any ideas what is this and if my tank is in potential danger?

[anthias]

here is another picture but this alge is only changing color but not prouduce any dust like.

[leebca]

The macro algae you show there is, I think, one of the Caulerpa sp. Caulerpa algae is not favored amongst marine aquarists because it can go through phases and sometimes also goes through a reproductive phase. It is very attractive and many herbivore fishes love to eat it. I personally love it. But with it comes some cautions.

These kinds of algae do best when they are routinely harvested. You have to keep pulling out healthy algae to keep the rest living well. Remember, there are just so many nutrients in the tank to feed the algae. What happens when the algae outgrows its food? It dies back.

When the 'leaf' of the algae begins to turn translucent it is a sign that algae is either entering a reproductive phase or starting to die back. That's the time to take action by pulling it out and thinning the culture. Ideally you will learn its cycle and 'be ahead of its cycle' by pulling it out before it goes into this phase.

Dying macro algae can crash a tank. That is, it can cause the death of many marine lives in the tank.

[anthias]

thank you lee I think it is in a reproductive phase because it seemd like the alge releasing something like asmoke.