Ive used play sand without any problems and it definitely doesn't inhibit rooting when i pulled up the tank it was the same as any aquasoil tank, the sand was used on its own and not as a cap though, and also it didnt turn anaerobic because i had mts and plant roots all through it.
It is quite fine, but i didnt find stirring it up was a problem this can also be an advantage especially with corydoras.
I would use play sand on its own but not as a capping sand.
Sent from my BV5500Plus using Tapatalk