help figuring out why im getting yellow spots on leaves

[freddyyola]

one my plant seems decently healthy except the leaves are all a lighter shade of green im not sure if it should be that color or if its the genetics but now its getting tiny yellow spots..

im watering with ph 5.9 -6.4 ever since i got my new ph pen a few days ago it seems all new growth looks healthy but 2 of my skunk widow berry plants have are a bit lighter green.
i dont think its a lack of nitrogen or any macro/micro nutrients since i feed with megacrop and i add a little calmag every few feedings just to make sure it gets enough.
im pretty sure im not over or under watering anymore since they are doing better and the new growth looks good but still the light green
i just want to find out what is causing leaf tips to die and yellow like in the third picture that way i can keep it from happeningthanks!

[NAKEDGARDENER]

Are they in soil? And what is the ph of the run off? At 5.9 ph going in I think that’s still too low, I aim for a ph of 6.4 to 6.7, adding tiger bloom and big bloom as well as hydroguard to my water brings ph a low of 5.8 ish so I adjust it up 6.5, now, when I measure run off the ph is again at 6.0 ish or just above, it’s that root zone ph I am trying to maintain at a range. Never trying to hit same figure with ph when I make up feeds, but in soil You definitely need to be putting in at 6.4 to 6.5 or 6.60.

[starramus]

"i got my new ph pen a few days ago" Have you checked the accuracy of your instrument? An easy and cheap reference is distilled water. Should be pH 7. I also double check with one of these kits.

https://www.amazon.com/General-Hydroponics-pH-Control-Kit/dp/B000BNKWZY/ref=sr_1_4?s=lawn-garden&ie=UTF8&qid=1536507767&sr=1-4&keywords=ph+up+and+down+kit

[D.A.A.S.69]

Looks to me like your plant might be rootbound, get her in a larger pot.