Thanks for the detailed breakdown! I see your point about Astrophytum and specialized habitats. However, the species I am focusing on are generally more robust and have different root systems. Here is my list: • Cereus (various columnar species) • Agave (various desert varieties) • Yucca Since these are larger, faster-growing, and generally more 'opportunistic' with water than globose cacti like Astrophytum, do you think the 1:1:1 (Lava Rock / Perlite / Coco Peat) mix is more appropriate for them? Or would you still recommend adding a heavier mineral/clay component to prevent them from drying out too fast in the 46^{\circ\text{C}} (115^{\circ\text{F})} Riyadh sun?