Lol, I wasn't asked, but I like Promix way more than Sunshine, personally. I use sunshine more though because it's much easier to get a hold of where I am at, but I special order ProMix whenever i can, especially the BX formula, it also retains a lot more moisture and I see healthier roots in it. But my views of Promix are opinion based, just like Mandala. Our opinions were formed on experiences, which were shaped by our growing technique. I probably grow different than Mandala so I love the stuff, they probably like to water more frequently, or whatever the issue was, and didn't like the product. I recommend giving it a shot. I've always said MG was shit, but I've seen a decent grow or two with it, so I'll just throw one pot outside this year with MG in it just to know if it's worth a shit or not. I can't just talk trash on MG for 4 years and not try it, lol. Did you know the BX formula has Trichoderma in it? Not only does it make happy roots, but it also keeps away root and plant disease!!
But don't start nutes right away on the little seedlings. It's okay to give seedlings very small amounts of nutes (always under 250ppm @.5 TDS calib) but more than often this just causes complications, especially for new growers. That little seed had roughly 2 weeks of rations built into it, everything that seed needs for it's first two weeks of life is already equipped. Just keep it moist, not dry, not wet, just moist and it will turn out great.