you said you are in a tent? this should be in the coco section. this is in greenhouse. you are inside.
i grow in a mostly coco perlite mix. drain to waste, top spray. 20 gallon pot trees. but what i do is different because I'm in a greenhouse. i would be running smaller pots with pure uncut coco if i were inside. i have big temperature fluctuations and more Sun and way more room.
forget about a top layer of anything. your canopy Will prevent evaporation. bottom layer of pebbles to help drain is cool. I'm not up in brands of coco because i buy in bulk, but there are 3 types of coco. super fine pith, stringy fibre stuff, and chips. mixture of all 3 is nice. including some chips Will make it do you don't really need perlite.