Thickness of acro polyps

[Obi-dad]

My acros are growing fine, however the thickness of polyps the polyps are less than many tanks I have seen. I have extension of the polyps that looks normal (millies and chips are fully extended during the day and night, others are more extended at night). It is just that the tentacles of the polyps are thin. My acros also look different in coloration, more 'pastel' like the zeo method - but I use a shallow sand bed, not zeo. I don't get the deep, intense colors that many have.

What affects the thickness of the polyps on acros?

Is the thin-ness of the polyps related to the pastel color?