soil sand cap Q
I'm a newbie about to start my first planted tank, a 20 gallon long. I'm looking for low maintenance, low tech (have too many other responsibilities to play with my tank very much in the next few years). I'll have lots of questions, starting with substrate:
I plan to use Miracle Gro Organic potting mix (sifted, then sitting in a bucket of water for a few days with daily water changes before going in the tank) plus some clay. For the cap, I'd like some kind of black sand.
What would be best: Flourite black sand (CEC = good), Petco black sand, or Tahitian moon sand?
Possibly relevant: I hope to have cory catfish so soft might matter, I have a high pH (8.4-ish) water, and I hope to avoid adding fertilizers. I'll likely add trumpet snails to aerate the substrate, but anaerobic pockets might still be a problem if sand is too fine and snails too few.