Please forgive a simplistic question, but I am new to 'enhanced substrates' – having always relied on dirty gravel/sand to provide food in all my planted tanks, plus MTSs and freshwater bristle worms to turn the substrate over and run things for me. (Some tanks have been going for over 20 years without a major clean-out, so I'm not unhappy with this method.)
I recently bought yet another second-hand tank that came with an unopened bag of Seachem flourite. I didn't want to bin it, so did some research.
If you need this stuff [at all] under your gravel or sand for root feeding, why have a two inch layer all over the whole floor of the tank? Surely, most of us only plant the heavy root feeders along the back and sides of the tank, so why have this expensive additive under 'open water' areas at the front where you want bare sand/gravel or at least just a scattering of tiny ground-hugging plants that could manage with a root tab or two – or the basic crud that filters down for free..?
So – a question at last – would it not be better to use this pricey stuff only in thick or thin strips, or even just small pockets where it would do the most good..?