AK48, Hydro, hard time identify problem w pictures

Hello All!

Doing my first hydro:
5 weeks in to flower
3 AK48 in bubble 60L res. (15.8 USGallons) cange res. every 14 days.
ph 5,5-6 (no digital meter, GHE PH liquid, ph7 from tap))
Nutes: switched from general GHE Guide to Lucas formula 14 days ago
EC: 1,2
400W HPs
Temp: day 24C/75.2F night 15C/61F

I got browns spotts on some older leafs that are spreading. And I think it´s a cal/mag problem. just want to hear from the pros. I have also found that some leafs are dry at the edges and the steam getting a red/bron color. I´m also thinking over fertilization, but it´s kind of strange the EC have never moved mush during the whole grow. And the EC have been higher (1,6). So that´s why I have lowered the nutes. Seems like the girls are living on water only?!?

So help a NooB out my friends!


Cal/Mag?



?

Help me pros, you are my only hope!

I would say over fertilization. I just did the same thing to mine. Also growing several Ak48 and they were burned more than the rest so they seem to be sensitive. Also with mine, I used the same mix values as before but this time they burned for whatever reason. Puzzled the hell out of me.

I'm not an expert. I had to ask here as well. Just relaying my experience. I also grow in dirt.

Sometimes meters lie.

Thanks, I heard the AK is very forgiving.. The thing is that I had a EC higher than 1,2 without no problem. I lowered it because it looked like the plant were not using the nutes.

Lowered the EC to 0.8 + cal/mag. Looks like they liked it.