No one can ID this acro. Please help!

[Matt Hursey]

Huge polyps. cant ID. had for 5 years with no growth then doubled in 6 months

 

[Salty1962]

Look like a Tri-Color, Valida

 

[Matt Hursey]

Look at the polyps in the second pic compared to the tricolor in the foreground. 3 times the size

 

[Diesel]

I don't think it's a acro at all but I can't be wrong as the time frame doesn't add up, if you had it 5 years it must have been a 12" colony.
More thinking about a branching cyphastrea, they are slow growing and have that behavior you describe.

 

[Tahoe61]

Looks like Acropora Effloresense to me. (not my images).

 

[Matt Hursey]

Efflorescence! I think that might be it.