Pps pro is a good system. I use it myself. I've heard if you have large plants that feed heavily off their roots in the substrate a tab can still be really helpful. Sword plants especially seem to like them. It's all about results. If the plants look healthy without them then no worries, but if they look like they need a boost then try a tab. Not all plants pull nutrients from the substrate, so tabs won't have much effect on plants that pull straight from the water column.