Both Flourish and Flourish tabs are really light on the major nutrients. They really only supply the trace elements the plants need. Depending on your bio load Nitrogen may not be an issue if you have a high nitrate level. Phosphorous and potassium may be issues.

Try adding some API root tabs, which are major nutrients only and no trace nutrients, in addition to the Flourish tabs. With the high light, you may need to dose the major nutrients.

Of course Carbon is a major nutrient too, and that also is lacking without CO2.