Been watching Father Fish on YT. I've been doing his setup without even knowing it until recently. Fluval Stratum and some crushed lava rock as a base in media bags with holes big enough for roots, topped with Flourite black sand. 6" in the back total and 4" in the front. Heavily planted and probably over stocked, two Marineland PRO 400s with the cartridges full of Matrix and Biomax rings. I don't ever need to do water changes, it's self sustaining at this point. My nitrates went up to like 20 the last time I added fish but are usually at 0.
But then again a bunch of people in this thread saying they use gravel as a substrate, which is just a terrible idea for planted tanks.