Jeff zone 8 N.C.

I just last year started using a coarse product too (Turface MVP) so can not be much help with comparing it to your river sand but my stuff looks about the same size of your sand but more consistent in size and has a porous surface. So far it has worked well for me. One warning if you use larger pots they are going to be heavy. I knew it would be heavier than my usual potting mix but was still surprised at how heavy. You will definitely have to water more frequently. That said if you are as dedicated as myself and want to grow those sensitive bananas you will figure it out. I use an appliance dolly to move plants.