Stylo turning white

[mmorrison55]

Yesterday I noticed a snail on my stylo and thought it was the reason for the polyps to have receded and showing the white skeletal structure, but 18 hours later, no snail but the polyps are still receded.

Is this something I need to start treating? If so, how have you successfully treated this?

 

[bubbgee]

From my milka stylo colony, the underside is always like that, but as long as flow is good the frag should be fine. That's usually the shading since you cant light up the underside of the stylo.

 

[Australian_Reef]

Is that area in shadow? It will go like that with no light.