When To Start Using My Nutes?

Im currently PHing my rockwool cubes. Once i start germinating my seeds i was wondering if i should mix a new solution with my nutes or just leave it distilled water with PH down. I have jungle juice.

The seeds contain enough food for approx 12 days. For germination I use water with a drop of superthrive, which is mostly a vitamin supplement. When the 2nd set of true leaves pops is usually when I start using 1/4 str nutes.

Alright thanks.....i will make a thread once they start for the whole grow