I hope this info helps you and your friend!

I'd say he should check pH too if he's not already doing that. I just recently started pH'ing, and realized my plants were experiencing a lot of sickness due to nutrient lockout. The roots could not absorb anything because the pH was too high.

This would cause issues for seed pops too.

Part 2 of this series shows how hydrogen peroxide helps with seed popping too.

Feel free to share this series with him. I hope it helps!

That's great to hear about you and @misshugo, and in my opinion, you've definitely earned a vacation bro, I hope you're able to get some nice relaxation soon with your girlriend <3