STN Issues - Green Base?

[Sangheili]

Been battling a small bit of STN on some of my acros (lost 3 or 4 wild colonies and 6 or 7 frags out of 100+).

Whats odd is that on two or three of the wild colonies, as they are STN-ing I have noticed the base turns dark green. So I cut one of these colonies in half today and it seems the green is down in the calcium skeleton also. What the heck is causing this? Is it normal necrosis or is this abnormal? Google is not turning up much for me.

Pics:

 

[Sangheili]

So some more digging on google suggests maybe this is a form of Boring Algae and that it is not really contagious to other acros around it. Seems to happen with wild/mari colonies (which is exactly where I have noticed this).

 

[WetWhistle]

The green boring algae releases an enzyme that breaks down the calcium skeleton as it bores through. It can cause the healthy tissue to pull back. It is believed that it can also facilitate attacks by other parasites and bacteria.

To stop it you can cut the green part out. So you will have to cut into healthy tissue. Or some believe it can be caused by a cyanobacterium like red slime algae. So some of the treatments for red slime could be used to treat this possibly. I typically cut it out whenever I have seen it. It is linked to higher nutrient loads in the tank, but it can also grow in low nutrient levels sometimes.

 

[Sangheili]

The green boring algae releases an enzyme that breaks down the calcium skeleton as it bores through. It can cause the healthy tissue to pull back. It is believed that it can also facilitate attacks by other parasites and bacteria.

To stop it you can cut the green part out. So you will have to cut into healthy tissue. Or some believe it can be caused by a cyanobacterium like red slime algae. So some of the treatments for red slime could be used to treat this possibly. I typically cut it out whenever I have seen it. It is linked to higher nutrient loads in the tank, but it can also grow in low nutrient levels sometimes.

Well it seems to have only affected the wild/mari colonies and only 2 or 3 of them at that. Have not seen any green on any frags.

 

[WetWhistle]

At least it only effects a few. Keep an eye on them. I have not seen it in my tank for some time but any time I did I had to cut the effected part out sooner or later. You could try epoxy on it as another option. That might cut enough of the light for the algae and you could stop it that way. That is possible to.

 

[Macdaddynick1]

For me it was low alkalinity, wouldn't let the coral create a new calcium deposit as soon as I raised it over 8.4 I actually saw growth, and stn stopped, also if you don't have enough flow around that acro you need to run high alk. I think acro can eventually outgrow the algae by creating more skeleton on top of it. But that's just a hypothesis.