All play a factor in zoa growth. Zoas vary wildly in their needs. Just in my tank I have some that refuse to grow if not fed often and in high par, i also have some that refuse to grow if fed often and in high par.
I use reef roids twice a week and have all my zoas under high flow to avoid things settling on them . The high flow to me has made a difference but it’s hit or miss and all tanks are different / See some pics Of my growth thx