There could be so many factors it's hard to say based on the info provided. Im still learning how to keep plants myself, but I will say a couple of things - prefaced by the fact that I know nothing about Turface, or how to use it:
You have enough light to create a need for ferts, so weekly flourish comp would probably help (if that's what you mean by Flourish), and definitely use root tabs under any heavy root feeders, like swords, etc. Dosing Excel every 2-3 weeks is practically useless. It only works for a day or two so if I were you Id do it every day or not at all.
If you would include some pics of the tank showing specific plants, filtration info, water change routine, parameters, etc, that would probably help the experts here give you better info.
You have enough light to create a need for ferts, so weekly flourish comp would probably help (if that's what you mean by Flourish), and definitely use root tabs under any heavy root feeders, like swords, etc. Dosing Excel every 2-3 weeks is practically useless. It only works for a day or two so if I were you Id do it every day or not at all.
If you would include some pics of the tank showing specific plants, filtration info, water change routine, parameters, etc, that would probably help the experts here give you better info.