Leaf problem second opinion - Soil grow

[Bobo636]

I have two special queens and a delicious seeds cotton candy going right now. I had to chop a white widow last week because of this problem. I had what i believe was a spider mite problem and sprayed them with neem a month ago. It seemed to stop the bugs from eating my plants. I sprayed again yesterday because I read that mites could cause this problem. My soil meter shows the soil is pH'd at 8.0 but runoff measures around 6.3. I'm thinking it is salt build up or a pH problem and i plan to flush next watering. I water less than once per week, nutes every other watering. I'd appreciate any opinions.

400w hps
general hydroponics. micro, grow, bloom, calimagic. nutes are pH'd to 6
foxfarms soil / 20% perlite
5 gallon pots
distilled water only
rh 30-50
temp 68-82f
3 weeks into flowering

may 11

may 13

 

[Savdout916]

Looks like it could be from over watering. Or a nitrogen deficiency.

 

[Bobo636]

After flushing with some calmag, the leaves stopped rapidly burning up. It happened on the two plants i was watering once a week. The other one pictured on the top left was fine and it was only getting watered once every two weeks. I'll give plain water next watering and see how it goes. I'm leaning more torward it being salt build up or nute burn. The plants i watered more often also got more nutrients.