biobizz root juice with rockwool ?

hi folks
at last ,i began !

i put my seeds into a glass of water and when they sink,i will put them into rockwool .( one of seeds directly sinked as soon as i put the seed into a glass of water ? )

should i presoak rockwool cubes with biobizz root juice ? or when should i begin using biobizz root juice and how much should i use ?

thanks guys .