Hard COral Diseases?

[Nexus13]

i should add they all died over a period of two days. I fragged one piece of nano acropora and it seems okay right now.

[i have crabs]

any changes you did to the tank?
were there all new corals?

[lorenz0]

what are your parameters...

[JDigital]

.. how old is your tank?

[Nexus13]

tank is over a year and half old

the hard corals that died have been in there for over 5 months

all my parameters are good (or so i thought)
pH = 7.9
Ammonia = 0
nitrate = 0
nitrite = 0.1
phosphate = 0
calcium = 380mg/L

yah all my fish are good,
soft corals are fine
just the hard corals all died very quickly.

i looked it up on the net and it sounds like
Rapid Necrosis.

anyone else had or know of this?

in terms of changes:
i did add a neon dottyback
and some porcelain crabs that didn't make it.

[Nexus13]

tank is a 29 gallon with a 10 gallon sump underneath

[fencer]

Yes it is RTN. There is another thread about this happening in the spring. I recently lost two colonies for no reason. Others have had similiar happenings and those people know how to keep SPS's