As promised, here is my tank with new substrate JBL Sansibar Black. It's kind of fine sand and my goldfish really love it, the grain size is so much smaller than my previous pool filter sand. But rinsing this kind of sand is a pain, took me 2 hours rinsing but the water is still a little bit cloudy after 3 days.
The Video (with background music this time YAY):
The Pics: