I keep my Zoa frag tank pretty stable like it’s a Reef tank with proper calcium, alkalinity and mag levels, about medium flow but I’ll let the Zoas let me know if they like or dislike the flow. I keep my PAR around 100-150 and again pay attention to Zoa behavior for too much or too little light. I do keep nitrates around 5-10 ppm. My Zoa frag tank is only 3 months old but seems to be doing well. I target feed my Zoas a couple times a week with a mixture of Reef roids, phytoplankton and oyster feast.