Issue with rockwool cubes

Hi guys.

I have an aeroponic system and I've used rockwool cubes as a growing medium.

My problem with them is that the roots, especially when I put the germinated seeds in them, aren't always growing or are growing very slowly. Many times seeds aren't sprouting at all from the rockwool. And the seeds aren't the issue because I buy them from a reputable vendor and they are always 100% germinating.

What could be the problem with them? Maybe I should try choosing a higher quality rockwool? Are there other alternatives that I can use for an aeroponic system?

Thanks.

do you soak the rockwool overnight before you put seed in ,also you need to soak with nutrients

Aeroponics are complicated. What temperature are you spraying? How often? What are your ppms and ph? What size rockwool are you using? What kind of lights? How far away? What is ambient temp and RH? How much dissolved oxygen is in your nutes? How are you keeping the root zone dark? Are you supplementing CO2? Are you using beneficial teas? What line of nutes are you using? Did you sacrifice a goat at midnight, when you popped those seeds?