The plant on the second picture has some yellow ed...

Hello @Peak81 ! From the fourth photo at week 14 i can spot several deficiencies. I can see potassium, nitrogen and zinc. Because of luck of information i will assume that you use a basic soil and you give no nutrients. So that's the number 1 reason that makes me think that you have deficiencies because the nutrients are not inside your soil. The number 2 reason is that if you don't give any liquid nutrients especially synthetic you can't mess with ph, salt build up and stuff like that. The number 3 reason is that if it was a ph problem you shouldn't have signs of nitrogen, potassium and zinc deficiency together. Nitrogen and potassium locks at low PH but zinc becomes more available. So if your PH was high you should have zinc deficiency and not nitrogen and potassium and if it was low you should have nitrogen and potassium deficiency and not zinc. Also zinc is number one micro nutrient deficiency for home made soils and i just saw at the comments below that you made your own soil. You should has put some amendments in it. Soil with just compost can't raise properly a cannabis plant. It will grow but it will not give its best. So my recommendation is to start using nutrients in order to fix it fast. If you don't want to use bottle nutrients ( i think you should use them until the problem is fixed ) you can make compost teas with guano,kelp meal, potassium sulfate (all organic) and other immediate absorption stuff. For the long term top dress your soil with amendments and cover them with some quality compost in order to be broken down by microbes and be available for your plant. Next time put some amendments from the beginning... Happy growing 👊