tsp superthrive,way too muchfor 2 liters...1/2 cap-capful per gallon for such young plants...
some people say no nutes yet, some say 25-33% nutes solution...
Zandor as always is right...being a rockwool user I might add; that if you are growing in soil, never use rockwool...the peat pellets are great...roots go crazy in that stuff,
but in my personal experience, side by side the plants I cleaned off peat pellets and placed them in netpots with just hydroton for DWChydro were not as successful as my rockwool plants(in a DWC setup), but if you are using a technique where you have rockwool sitting in solution constantly, you can experience all the problems Zandor mentioned...one more thing as Zandor mentioned above, you must soak the rockwool in ph adjusted water overnight, then give it a good shake or 2 like shaking out a paintbrush... never (using dwc) pour water or nutes through netpot and rockwool it will rinse your semi-dry rockwool into res and your ph will go crazy, always add your solution thru a filler tube, pump it from a main reservoir, or pull up the top and pour it directly in the res...hope this helps...latewood