I think I'm a gritty mix failure. I spent a ton of cash replanting my succulents into gritty mix and so far I've lost several of them including this cactus which turned black and rotted. When I took it out of the pot the roots were still wet so I guess this mix (Bonsai Jack's Succulent Soil) stays wet for longer than I'd assumed. My jades seem to be doing well in the mix (Thank God), but everything else is going to crap. I've only been watering every 7 to 9 days in the clay pots and about 10 to 12 days in the deeper glazed pots. I didn't think that would be too much and I didn't think you could over water gritty mix. I have a plant fetish and I love the gritty mix but figuring out the proper watering schedule is frustrating. Did this cactus suffer from over watering or something else? I've also been using foliage pro 1/2 tsp per gallon when I water. Maybe I fried it with fertilizer???