So you're using liquid litmus...

I'm just thinking that with all that perlite in there this is almost a hydro grow.

6.2 wouldn't be too bad, but you can't tell 6.2 from colour.

A couple of weeks ago, around week 4 you should have peaked your ppms to 1.0-1.2ec or 700-840ppm.

You may say your plants are not undernuted but i have seen signs on your leaves.

You have an undernuting problem, and i believe this is also caused through a ph lockout in your medium as well as feeding the wrong levels of nutes throughout veg'.

The answers are always the same.