Hi, would you recommend the fluorite black gravel as a substrate or the fluval stratum?
Flourite is inert, hard to plant into and too expensive for what it brings to the table.
Stratum is no cheaper than ADA soil in my part of the world, and it isn't as well refined nor does it claim to supply any nutrients.
If I were to go inert, it would be a plain sand of any type (Blasting sand, pool filter sand, astro turf infill sand, aquarium specific sand) or a very fine inert gravel such as Caribsea super naturals.
If I were to go with a buffering substrate, it would be ADA, Landen or Tropica soil.
If I were to go in the middle of the two, it would be calcined montmorillonite clay (Shultz aquatic plant substrate, Safe-T-Sorb, cat litter etc.)
If I were to try something new, mienralized top soil capped off with sand or calcined montmorillonite clay (probably not the best approach for new planted tankers as dirt brings in a lot of "mess" that can easily lead to algae and inconsistent results.)