Can i use pk13/14 in soil

I am currently on week 6 of flowering , i added pk13/14 in weeks 4 , weeks 5 and week 6 , some of the leaves are going yellow and some of the leaves are brown and dying .
Am i using too much pk13/14 or is the yellowing normal at this stage , or could it be a nitrogen problem , if its a nitrogen problem could i put a small amount of grow nute in my tank please reply any advice welcome cheers

Do you want to share with us how much you used, and how often? Or is that a big secret you need to keep?
Maybe you could inform us about the strain you're growing?
Or possibly the pH you are applying it at?
The temperature of the area?

You're probably short on Magnesium as a result of an imbalance.

Strain Is jack herer grown in soil ph 5.8 temperature 29 degrees celcius

Doesnt it say on the bottle to use it once in the 4th or 5th week of flowering ?

You could be over doing it

Use for one week only when dime size fruit appear

i use the whole canna line in coco and aqua i only use pk 13/14 for one week now when dime size fruit appear i have tried two weeks 2nd week at half dose but also had some yellowing in my super lemon haze and a home made strain m.o.d so now i use for one week only ,with great results and no yellowing but i also use whole canna line

"there comes a moment during the plant’s development when the need for phosphorous and potassium increases greatly. If CANNA PK 13/14 is given at this moment you will satisfy the flowering plant’s increased needs and the fruits will achieve maximum development" - canna site