Rapid, uniform, wide-spread leaf yellowing - flowering week 5

Hello Pawsgrow, you give the answer yourself already... you haven't been monitoring pH and cannabis can only absorb the right amount of nutrients when the soil is in between pH 6-7 You only need a pH adjuster like the organic pH min from Biobizz and a cheap pH measuring tool will do the trick. They are both very cheap and this small investement will give you alot of weed in return!