Whats going on here? Cal-mag def? Potassium?

I am entering my 5th week of flower and beginning to have some issues. I first started to notice the tips of the leaves VERY lightly burned, which is the norm for most of my grows because I keep them fed well, however it never progresses into anything more than tip burn.

I will also add, that I am new to using coco... But so far my grow has looked amazing, zero issues up until now. To me it looks like it's either one of the three things....

- Calmag deficiency
- Potassium deficiency
- Excess Potassium


I am including some pics of the leaves.... The issue is not widespread, but slowly getting worse. It is more noticeable on the more upper leaves of the plants. I increased calmag lastnight in the new reservoir mix from 2ml per gal to 3.5ml per gal, dropped base nutes from almost full strength to 3/4 strength... ph is consistently between 5.8-6.0. I noticed my leaves were pretty dark green before all of this started, which is why I backed off the nutes a bit. I keep the medium moist but not wet, multiple feeds...

Temps are between 75 and 79 degrees.... RH is consistently around 45%... Have plenty of fresh air and air movement..

I do coco, will try to help.

What all is in your nute mix?
Feed Ec/ppm?
Have you checked the runoff ppm to see if it's higher or lower than feed ppm?

Maybe...

Easy to do, I've done it.
(no flushing with water - always with nutes just lower ec, but you prolly know dat)

TintEastwood said:

I do coco, will try to help.

What all is in your nute mix?
Feed Ec/ppm?
Have you checked the runoff ppm to see if it's higher or lower than feed ppm?

Maybe...
View attachment 4624709
Easy to do, I've done it.
(no flushing with water - always with nutes just lower ec, but you prolly know dat)

Click to expand...

I use Advanced Nutrients Sensi Coco line... I use their A & B at 3/4 strength, Big Bud, Nirvana, a little supplemental calmag and just recently started adding MOAB at 1/4 tsp per 5 gal when they recommend 1 to 2 tsp per 5 gal. So the moab dose is extremely low, but now that I think about it, these problems rose once I started using the moab... I also mixed my reservoir a little too heft last week which could possibly be the culprit as well. They looked extremely great up until the last few days... I dont measure EC or ppms... I have not done that nor owned one of those pens in over 18 years and never had this issue before... I will probably get one though for my next run just to be on the safe side...

I am thinking about eliminating the moab completely and reducing the A&B to 10ml per gallon where it calls for 15 ml per gallon at full strength. I have been feeding at 12ml per gal. I don't really wanna do a flush in coco, but maybe reduce overall nutrients and get lots of runoff going? I don't ever water till runoff, maybe just once per week. Maybe salt buildup?

Thanks for the prompt reply!

This is how it looked just last week!

Moab is equivalent to MKP.
Potent stuff. Here's the ppm breakdown.



Your grow looks great. Nice work!

This is kinda how I roll...still learning.

TintEastwood said:

Moab is equivalent to MKP.
Potent stuff. Here's the ppm breakdown.

View attachment 4624771

Your grow looks great. Nice work!

This is kinda how I roll...still learning.

Watering Coco - How to Water Cannabis Plants in Coco Coir - Coco For Cannabis

Coco Watering Guide. How to water cannabis in coco for maximum growth. Includes guidelines for coco watering frequency and a coco watering schedule.

www.cocoforcannabis.com

Click to expand...

Man, now that I think more about it, I believe I know what's up... So as I said previously, I have one single 50 gallon reservoir and all plants feed off that one rez... However, it is only the front half of the room expressing these issues. The rear half of the room is on a separate pump and I noticed I get runoff in the back half of the room a minute or so sooner than the front half. The pump in front water's a little slower than the rear. So I believe this leads me to believe I have salt buildup in the front half of the room thats on that specific pump.... Since I hardly never get runoff...

Damn, why didn't I notice this sooner??? Smh....

So, should I just reduce nutes to 3/4 and water all plants till i get plenty of runoff? Half strength? What do you think??

Flushed them all with ph'd water (water only), which was ph'd at 5.9. Then mixed a new reservoir and with 3/4 strength base nutrients, big bud and Nirvana. Cut out the moab for now... May give them some a couple weeks before flower and at that time I'll reduce the base nutrients to half strength, this time.

When I was flushing a few of them had runoff of 5.1-5.3 ph... So even though I don't have a way to measure EC and ppm, I do know something was not right in the medium... I bet it was too much salt buildup. After flush, I ran the new mix of nutes thru till I got a ph of 5.8 so we will see what's up in the next few days....

They were looking happy before bed time this morning...














I just love that PNWHP/Black Domina x Super Skunk in the last pic... Buds already almost as thick as my wrist, skunky, hashy, light citrus and straight funk....