Give them a flush,and then get some recomened fertz,
and follow the instructions on the bottle its much easy mate!
For starters at least..
I am also beginner and i dont have a ppm meter either.IAM jus going by whats on the bottle ,,i know for a fact that i could probley get a better yield if i knew what i was doing a bit more(this is how we learn) ,,,BUT at the end of the day its a WEED.
I MUST GET A PPM METER NEXT ON MY LIST lol.