Astrophytum seedlings

[Astrocereus]

So I recently started growing cacti. From what I have been reading that the genus Astrophytum can be tricky. Well i have been lucky with other plants so i thought i would dive in head first, so to speak. I just wanted to show off my seedlings at 6 days old (cacti are a month old). let me know what you think. i have two different mediums going right now one is 70% perlite and 30% organic potting soil. The other medium is a mix of 60% perlite, 30% organic potting soil, 10% sand.

[Lafleurz]

I want to know if you can help me with adding a message to know it?