Zoas not opening - white encasement

[RaymondL]

Need some help on this - as shown in the picture only one head of the zoa is open, the rest are closed and have a white film or something on the head.

Thoughts what this is and what I should do to save them?

Thanks

 

[HankstankXXL750 Verified Sponsor]

It is not very clear or sharp so hard to tell. Many Zoa’s have a different color at the end of their tubes when closed. Would need a little more info? Are they in direct flow? They do like some flow but not direct?

What are your parameters?