Picked up a hydroculture orchid kit at a garage sale for five bucks. It
came with the media (fired up clay), the culture pots and interior pots, as
well as the water level indicators. The instructions called for an
overnight soak in a rooting compound/nutrient mix. But there was no rooting
compound or any other fertilizer-like powder in the kit.

Trying to understand whether any ordinary rooting compound would work the
same?
Can I substitute a GrowMore 20-10-20 and soak the clay media in this?

Assistance would be greatly appreciated.

Thank you.
Mariana