Yes, no problem for Zoanthus gigantus.
If they had the long stalks before, they'll keep it like that, most of the time.
Long stalks are normally the case when the polyps were found in low water flow environments, but not the rule!!!
I've seen Z. gigantus in high water flow environments and on wave action / exposed environments with relatively high stalks. I've seen them with short stalks in the same type of environment. I've seen them with long stalks in bays with slow water motion and high light exposure.
You can keep them under metal halides and they still will have the " long stalks".
I did in the past.
So, generally speaking, Z. gigantus has long stalks and those yellow/green lines when closed.
Nothing to worry...
The more light the better for them. Keep in mind you need to have an appropriate light for your system, not a 400W over a 20gal! Keep temp about 79F if you can.
About long stalks...
Sometimes in the same colony, or with frags from the same colony, placed in different places in the tank, we could notice some polyps with smaller stalks than others and most of the time the light and water flow will define such differences. Not a big deal.
Grandis.
