Grey encrusting algae

[LittleLakeReef]

This encrusting grey algae is taking over my tank and killing coral and destroying my coralline algae. What could it be and what can I do to stop it I’ve tried brushing it off but it trust to like dust and is dang near impossible to get off

 

[Tahoe61]

It looks like a different type of Coraline algae. There are red, and green varieties..
Are you sure it's entrusting quick enough to kill a healthy coral.

 

[Mppp]

Hard to tell if rock you have is carib sea rock which has a coraline purple look in spots or if you have established live rock with some purple coraline as well that was established before this gray algae you're referencing for starters. I will say when my phosphates rise a bit the purple coraline algae fights some red/cyanobacteria starting before lowering phosphates again that I suppose can look gray depending on lighting. Sorry for boring age old question(s), but it is important what is your Nitrate level, phosphate level, and minimally Alkaline?

 

[LittleLakeReef]

@Mppp @Tahoe61
This is old rock tha has grown its own red purple pink blue and grey coralline algae over the years and now this almost dusty brownish grey is growing over it much faster then the coralline that was previously growing it’s almost growing over it and it’s taking over extremely fast it has grown up the back of the toad stool in the photos and has turned the back side of it grey and is killing it
My all stays between 7.3-7.5 my nitrates are below twenty usually around 16ppm
And my phos is below .1