With growing marijuana its best to ease on the side of caution when it comes to neutrients and soil.
I've found with seedlings in small pots putting in too much perlite you can get caught off guard if you miss a day watering them and they dry out and die quick, but if you use a little less and ONLY use water when you transplant into the larger pots put the perlite right to it so the roots are searching for water. Usually about 1/4 perlite will do good in the final soil mix.
Get a PPM meter to see how much for nutrients is in your water and only SLOWLY add them in when doing a soil grow, and don't go above 700-800PPM, that's about as high as you want to go towards the middle of your flowering cycle, dont be confused by hydro systems that use a much higher concentration of 1000-1200.
Also mix in worm castings or blood meal in your soil to give your plants all the N they will need, so you can focus on the other nutrients.
Good luck!