Personally, I have mostly low tech tanks (only one high tech). My growth is attributed to a few things:
Water column, ferts, light. Considering most of my tanks are Nano, low-medium light with low bioloads- I need to be very diligent with controlling my ferts. I find root tabs unpredictable.... If for some reason I realize I need to cut down on ferts- then your stuck digging things up trying to find the root tabs! (did it once.... with a fluval edge- so I ended up hurting my fish trying to dig through a 4 in hole in the lid!).
So I prefer to dose the water column.
However, with your situation of just using flourish is obsolete these days as its missing some important nutrients. Therefore I would ask you to check out Thrive C... its more complete and its 1 squirt per 5 gallons. It does contain carbon as well, but you can also dose Excel and your plants will rocket to the sky!
Giving back creates a virtuous cycle that makes everyone more successful (as long as they cycle!)