Using EC meter for measuring content of fertilizer in soil.

[Xakmo]

Hello guys new to forum here I have a question for y’all

My plants are autoflowers and are entering 8th week since sprout.

They are in 4 gallon ( 15l ) pots in soil under HPS and LEDs

Temperature of the room is 26-30* C ( 80-85*f)

RH : 50%

Im using Green House seed company mineral line of nutrients with “Hybrids” as the bloom nutrient. , Chelated calcium and Booster PK+ from the same manufacturer as additives.

Along with some off brand algae aminoacids and vitamins.

This is my first grow using these nutrient company and I have been following their spreadsheet for Hybrids/Soil

Giving them 3/4 of recommended dose for the most of their life with no problems just slight deficiencies nearing last week , so I upped the nutrients to full dose consequently the yellowing from deficiencies stopped for a few days then started to be more apparent and the growth slowed down.

I adjusted pH with every watering and feeding to 6.2-6.5

My watering schedule is ; water - feed - x - water - feed - x …

Feeding every other watering

Currently im giving 800ml of water and then 800ml nutrient solution the next day, then water again when needed.

Im not sure if Im giving them too little or too much nutrients so I noticed on the spreadsheet theres an EC/PPM value for every fertilizer and the total EC /PPM required for every stage/week the plant is in.

But im not sure how it works.

I got an HM EC meter and found out this ;

Tap water EC is = 0.6



From my understanding I should be able to read are my plants underfed or overfed by looking at the EC value of runoff when fertilizing.



So my current desired EC value is 1.6 and my tap water EC is 0,6 that means I should be giving them 1.0 EC worth amount of nutrients to set the total value of EC to 1.6 and then whilst feeding them measure the runoff.

If its the same value or close to the same value (1.6) then that means they are eating right ?

If its lower than 1.4 I know that nutrients need to be higher

If its higher than 1.7 I know that I need to ease off on the nutrients?

Or if the EC of tap water is 0,6 and the EC goal is 1,6. I should add 1,6 EC worth of nutes so the total EC comes to 2,2?



Today is feeding day

What should I do?



Give the plants nutrients like one of the ways mentioned above and measure runoff

or

Flush the medium with pure pH-ed water before its too late and they are fried.



My plant’s genetics are probably unstable or something caused few of them to dwarf out and produce large main cola and satellites that are mature and ripe ( those are the ones affected by yellowing the most ), on the other hand some plants are almost double the size and just started flowering. ( not much if any yellowing )

How do you recommend feeding them when theres so much difference in development/stage.

Obviously the ones further in flowering would require different amount of nutrients right?

So how do you go about doing that when you have allot of plants without making it too complicated for a larger setup.



What do I need to do to find out where Im at?



Do I measure separately the runoff from group A and group B to find out their feeding requirements as maybe the ones deeper in flowering are yearning for bloom nutrients or they are having too much nitrogen for their stage?



Heres some more info ;

Light cycle : 20/4

Cultivar : Northern light Auto

Soil ; pre amended for 3-4 weeks

6.5 PH

Airflow is good

No prior issues other then small nute burn on first feeding ( fed a bit too early ),

Once was late with watering ( drooping )

They had absolutely no problems other than small deficiencies showcasing in lower leaves until few weeks into flowering

I also upped the nutrients at that time because of evident hunger so Im guessing they could be over fertilized going from 3/4 to full dose.

Someone told me from his view it could be N toxicity and K deficiency.

The soil ph is 6.9 if the slurry test is correct.



So my question



Can someone teach me how to use EC meter to find out am I deficient or sufficient in nutrients ?

How to use the chart EC recommended value for mixing the nutrient solution.

Also how to feed the plants adequately when they are in different stages of growth without making it too complicated or laborious for a medium large scale setup ?

What would you do in my situation considering today is feeding day and Im still not sure what the cause of the problem is.

Also I noticed one big plant almost has grown a new main cola I would say and I found that branch to be laying down bent over flat
Is that normal?
Is it from the weight or something else is happening?
I think its in the video I have some problem uploading media on the forum

Any help is appreciated

Thanks

X.

 

[Xakmo]

Someone told me it’s definitely chronic calcium deficiency.
Since ive been giving 0.5g/L and he says I should be giving the full recommended dose.
Is that right if so How do I correct it?
Is it too late?

 

[Homesteader]

Hard to tell exactly and probably hard to fix anything at this point. Looks like lockout to me but again hard to tell. P/K are often the culprits though....I don't know about EC but I wouldn't think you would get a very exact measure.
Maybe trim the yellows and let a little more air flow in there. How is your light?
You running again after this one?

 

[Xakmo]

Hard to tell exactly and probably hard to fix anything at this point. Looks like lockout to me but again hard to tell. P/K are often the culprits though....I don't know about EC but I wouldn't think you would get a very exact measure.
Maybe trim the yellows and let a little more air flow in there. How is your light?
You running again after this one?

Yes im running again for sure
I got some auto seeds ready from Fast Buds both cup winners tropicana cookies and gorilla cookies.
Light is lumatek ats300w pro at 100% about 60cm from canopy.
Hps is 600w also about 60cm light distance.
What can I do now to help them
I cant flush
Try to give them more Cal?

 

[ArtfulCodger]

IMO, you're over-fed. The brown tips on every plant are evidence of nutrient burn. I monitor the EC/ppm of my runoff water to get a sense of when to feed. I feed only when my runoff falls below 1.8 EC (900 on the 500 scale). The feed charts on nute bottles pretty much universally tell us to feed too much, especially for autos. My advice is to stop feeding, and get a runoff reading so you have a sense of where you are in terms of salt in the pots.

 

[Homesteader]

Good advice IMO.