brown spot

hello
my problem is brown spot what comes sunleaf and then leaf dieds
strain is:critical auto nevilleshaze 3 weeks 24/7 lights

my setup is dripfeed roots out,clay balss 3l pots running 24/7
there is air stone in res,
nutrients level i keep 20l i chance every day 10l nutrient,i use canna grow 10-15ml/10l+everyother time 10ml rhino skin and 10ml diamond nectra.
ph drops 24h 4.7-4.9 and ppm stay or litle drops,
i use tap water what is 93ppm/8,01ph
then its come 340-360ppm and ph is 6.0-6.3
i have mark start point,i now when tap res pure water

i fuck up start,give them too hig ppm,and one is drying and dead up
that what i asking recowery well,its didint show much over feed problem at all
sorry,i dont take photos my growing and i now cannabis need night time but now they have to survive,its cheaper me keep lights on or using heater

Sounds like you need to start feeding them heavier. Your ppm are too low.

its spear,leaf curling and dry i think it could be too much silica or humic acid?
i drop both off my feeding chedule,only canna grow a/b 15ml/10l lets see what happend

You need to increase your nutrients strength. You should most likely double the strength of you nutrients, a range of 600ppm-700ppm would be more ideal.

You might also want to think about a timer for you drip system. roots do better when they have some dry cycles.

You say you started them at too high of a ppm level. What was the ppm level you think you where feeding too high with?

These brown spots you mentioned, where they on the tips of the leaves or where they spots on the leaf surfaces?

hi happy new year for all
its starting near leaf tip,not like nute burn then its spears and kill leaf,i lift ppm about 450 next weeks i lift it near 700ppm,then chance flower nutriens,i leave silica and dn for now lets see what happend