SPS questions

[houstonreefer]

I have some questions regarding my SPS.
I have a pink birdnest in my tank. At night and early morning i saw emeral crab stick on the birdnest (2 times). Note that there are some dead branch on it. Does emeral crab damage the coral?
My last qestion is that my two arcopora seem to have extended polyps at early morning when the light is not on yet. It is normal or ....?
Your opinions are appriciated.
Thanks in Advance.

 

[MiNdErAsR]

The crab *could* be eating the coral...or it could simply be eating algae growth from the skeleton. IME it's normal for acros to extend polyps at night for feeding, but will change their habit as they grow acustomed to your feeding schedule.

IME, IMO

 

[wildbill]

My tank is mainly sps corals and have not yet seen an emerald crab damage my light green birds nest. I've had this coral now for 6 years. Also most corals extend there polyp's when the lights are off because they receive some nutrition from filter feeding. I believe all sps's and lps's receive some nutrition this way. In my tank I can see thousand of little animals swimming around around and hour or two after the lights go off. Don't worry about the birds nest if its healthy its soon be growing new polyp's.

Bill

 

[houstonreefer]

Thanks guys

I dose DTphytoplanton when i get home but before light off.