Random nectrotic regions, CNS17 in Coco

Have gotten this the past 3 veg runs, this time it's worse. It fits a few deficiency pics, mainly Mg-, but I know I have enough Mg and the pH is alright. Any thoughts?


83watts/sq-ft (4000w in 8x6 room) Metal Halide
75F-82F Day, 65F-70F Night
1500ppm CO2 controlled during lights on
House and Garden Coco
4 Gallon pots

RODI Water
CalMag+ 5ml/gal
Botanicare CNS17 Grow 10ml/gal
Botanicare Fulvex 5ml/cal (as Mg supplement)
Pro-Tekt Silica 2ml/gal
Roots Excel 1ml/gal

pH going in has been 5.8 to 6. PPM going in has been 700. It comes out at 350-400 and 6.4-6.6 pH, but I know your not supposed to judge coco runoff pH. The fact that the runoff is half the ppm that I put in, could these be starved for food and need way more? I doubt it, just looking for opinions here.

You sure you don't have a fungal issue? Necrosis is generally a botrytis.

That kinda looks like a cal-mag issue to me. imop

I think the "rusting" of the leaves is a CalMag issue. I do coco and had something similar looking before and just ignored and it was all fine. It's apparently a known issue with coco. Yours also look a little over-watered possibly too. GL

hydrolyzed said:

Have gotten this the past 3 veg runs, this time it's worse. It fits a few deficiency pics, mainly Mg-, but I know I have enough Mg and the pH is alright. Any thoughts?


83watts/sq-ft (4000w in 8x6 room) Metal Halide
75F-82F Day, 65F-70F Night
1500ppm CO2 controlled during lights on
House and Garden Coco
4 Gallon pots

RODI Water
CalMag+ 5ml/gal
Botanicare CNS17 Grow 10ml/gal
Botanicare Fulvex 5ml/cal (as Mg supplement)
Pro-Tekt Silica 2ml/gal
Roots Excel 1ml/gal

pH going in has been 5.8 to 6. PPM going in has been 700. It comes out at 350-400 and 6.4-6.6 pH, but I know your not supposed to judge coco runoff pH. The fact that the runoff is half the ppm that I put in, could these be starved for food and need way more? I doubt it, just looking for opinions here.

Click to expand...

That is exactly what that run-off ppm is telling you! Bump it up.
I'm usually at around 1.5EC at around 3.5 weeks veg. I run at about 1.7-1.8EC in flower.
I ran cns17 in coco(both of the old formulas, and the only formula made now) for a couple years, and 15ml/gal is where it is at. Cns17 is awesome shit. Allot of my pals still use it.

My starting water is 70ppm. I was adding about 3ml/gallon of calmag. That was it! Besides the 15ml/gal of base. Grow, bloom, or ripe of course. At my buddies spot, we add 4ml/gallon of calmag because he starts with RO. Nothing else, except a little ph adjustment. we kill it
.