Indoor Flowering plant in peril!

[Cerul]

Hi guys,

I'm growing a Hogs breath auto from 420seedguy hydroponically. It has been under 24 hrs of light (2 autocobs and since flowering started I added my Meizhi 300W but only the red flowering lights).
I'm following @greenjeans method of growing in a sterile medium.
I've been using Botanicare's CNS17 line and supplementing with CalMag and SilicaBlast. the plants are a month into flowering and I noticed these spots 3 weeks ago. I've changed the water but the spots have since increased to more leaves. It is only affecting the new growth on top and the plants overall growth has not been affected. Also all the new top leaves have been very skinny compared to the lower foliage.
Please help!!!!

 

[Waira]

...how close are those lights? Symptoms look like Ca defc.,.... I'm not familiar with that nute line, or "sterile" mediums-?? .... what are the T and RH%? ..might be a bad combo of these making for bad VPD conditions,...and/or too much Ca-Mg and you now have some sort of uptake interference... that it's top biased hints that lights are too close, Tnad RH% not in proper range,... You say these plants have been flowering for 4 weeks, or a month old and now flowering?

 

[namvet25]

What do your roots like and are you ph'ing your water/

 

[Noob420]

I have used the cns17 line when i first started growing a couple years ago, and my firs grow looked just like yours. I grew in coco and perlite under 250 watt hps. My second grow i started with using cal mag with tap water but, was suggested if i didnt see any cal mag issues not to worry about supplementing cal mag. My third grow i left cal mag completely out and had no further issues. The cns 17 should have enough cal mag in their to get you through.

 

[Cerul]

Hi @Waira,
Sterile medium means I'm using a product like Watermax to keep the DWC bacteria free(or as close that you can get to being bacteria free). The temps in my tent are around 72F and Humidity is at 78%. The plant is almost 2 1/2 months old and has been flowering for a month. The lights are 10 inches away and are pretty cool to the touch.
I check pH once or twice a day and the roots are very good and appear clean/white.

 

[Waira]

...roger that mate,... OK, I think the lights are too close; it's not always about T, it's about the sheer intensity, just too much,.. this can compromise the functioning of the machinery in the chloroplasts,.. leaf edges and tips are showing stress,.... Also, 78% is too high, adversely affecting transpiration (read the VPD article here in the Reference section),... between the two, and that it's so top biased, tells me the combo is screwing with Ca uptake,.. raise the lights, LST, anything to reduce the brutal intensity of those COB's and the other LED,... gotta get that RH% down too,.... you'll see why when you read that article, and see the video,...