nutrients deficiency expert needed!

[Owais]

4 autoflowering 3 of them are in an preflowering stage i guess, they sprouted february 7th so they are about 22 days old except the 4th one is one week younger, however the 3 big ones showed a magnesium deficiency about 11 days ago or so so the followed feeding after i discovered the symptoms i added the minimum recommended dose of magnesium nutrient from GOLD LABEL NUTES called (Ultra Mg) .25mL Per Liter , the problem somehow stopped from spreading all over the rest of the leaves with the yellowing 2 days ago i fed them again with .5mL Per Liter but still i get new growth with a yellowed tip leaf! it's driving me crazy and i'm thinking there's another problem beside the magnesium deficiency probably!
I'm using GOLD LABEL nutrients the tent environment is very good temp and humidity. they are under 1000watts Metal halide

2 plants are white diesel haze
2 plants Super skunk and they are all autoflowering
2 plants of one strain has a different symptoms regarding the mag def the other 2 plants with the same strain has different symptoms
the small one is just one week younger than the others but yet it's significantly smaller than the others..
any output is appreciated fellows! thanks for your time

here's some pics

 

[DirtyMcCurdy]

How often are you watering? Could you be overwatering? What pH is the run off after you feed/water? What type of soil? Don't know what you're using for nutrients but looks like it could be the signs of a micronutrient deficiency.

 

[nomofatum]

Magnesium, likely low PH though. Only on the two of them though.

 

[Owais]

How often are you watering? Could you be overwatering? What pH is the run off after you feed/water? What type of soil? Don't know what you're using for nutrients but looks like it could be the signs of a micronutrient deficiency.

I water once a week, whenever i find the soil is close to dry, i dont check the ph of the run off but i water them with ph 6.5
The soil i'm using is called van egmond..

 

[Owais]

Magnesium, likely low PH though. Only on the two of them though.

Strange, they all get the same water same mix, the ph meter says the mix is 6.5after i manage to make it that high with adding some ph up, probably the reading is not veey accurate, u think i should try do it 6.9 in case the reading gives me a higher than the real ph number? Mag is added in the last 2 watering/nutes then maybe the problem is just ph and the plant is finding it low ph and cant absorb the mag very well?

 

[nomofatum]

Strange, they all get the same water same mix, the ph meter says the mix is 6.5after i manage to make it that high with adding some ph up, probably the reading is not veey accurate, u think i should try do it 6.9 in case the reading gives me a higher than the real ph number? Mag is added in the last 2 watering/nutes then maybe the problem is just ph and the plant is finding it low ph and cant absorb the mag very well?

Sure, but also measure the ph of the water that comes out the bottom. What is it's PH? And you should have a backup PH testing method (liquid chemical test or a second calibrated meter), you need this to verify your primary device from time to time.

 

[DirtyMcCurdy]

Gotta check run-off pH. The only way to be sure what you have going on. Make sure your meter is accurate or throw it away and get a new one. I cannot stress pH enough. What type of water do you use? Do you let it set out at least overnight before using? Tap water sucks even through an RO filter, unless you set it out or bubble it for 24 hrs. Adding nutes and pHing fresh tap water is going to give inaccurate pH measurements.

 

[blowincherrypie]

Tap water is generally the best water you can use.. Unless you cant drink the stuff

 

[DirtyMcCurdy]

Tap water is generally the best water you can use.. Unless you cant drink the stuff

Or its in the high 300's coming out of the tap. Hopefully you're joking

 

[Owais]

Tap water is generally the best water you can use.. Unless you cant drink the stuff

The tap water where i live is not even good for human drinking :/ i use bottled drinking water, maybe my ph meter is screwed i should pass my the store today and buy a new one or get it recalibrated

 

[DirtyMcCurdy]

The tap water where i live is not even good for human drinking :/ i use bottled drinking water, maybe my ph meter is screwed i should pass my the store today and buy a new one or get it recalibrated

If you doubt and/or have no way to check your meter, you need a new one. Definitely get one that can be calibrated and make sure to get the buffer solutions.

 

[Owais]

If you doubt and/or have no way to check your meter, you need a new one. Definitely get one that can be calibrated and make sure to get the buffer solutions.

Matter of fact i did calibrate it like 5 weeks ago before i start growing this time but the meter is a little bit old, about w years old and been stored for about 2 years never been used and it's not the best brand, i should have invested some money from the begining on a new one

 

[blowincherrypie]

Or its in the high 300's coming out of the tap. Hopefully you're joking

Weed requires a special water? I used to buy that crap 20-25 gals a cpl times a week (RO/super filtered etc)... I used it with AN.. I was stupid squared..

 

[DirtyMcCurdy]

Nobody mentioned special water. He says he uses bottle water cause his tap is crap. I said RO water, if he's using a filter, still needs bubbled. Not that he shouldn't use RO water. That's what I use. I don't but any special water nor was I telling him to. Special water?

 

[DirtyMcCurdy]

Matter of fact i did calibrate it like 5 weeks ago before i start growing this time but the meter is a little bit old, about w years old and been stored for about 2 years never been used and it's not the best brand, i should have invested some money from the begining on a new one

This is what I use. Nothing special. Somebody will cut it down Im sure. But it wasn't that much and its always real close when I do recalibrate it

 

[hydroMD]

Nobody mentioned special water. He says he uses bottle water cause his tap is crap. I said RO water, if he's using a filter, still needs bubbled. Not that he shouldn't use RO water. That's what I use. I don't but any special water nor was I telling him to. Special water?

Actually a filter takes out chlorine, but leaves some hard metals, while RO takes everything out... which is why ppl often need to add a micro afyer using RO.


Now for the diagnosis,

1, your ppm is too high. Those yellow tips are nutrient burn. You should either drop your PH or start alternating nutes and fresh water every watering.

2, numofatum is spot on with the magnesium with the more yellow girls.

Unless they are clones, they will each want a tiny bit different nute solution. Best thing to do is find a happy medium that works for all

 

[Owais]

This is what I use. Nothing special. Somebody will cut it down Im sure. But it wasn't that much and its always real close when I do recalibrate it

How bad do you think that affected the overall plants health and the quantity/quality of yeild when i harvest? Assumed the ph will be fixed in the next watering in 3-4 days from now ;/

 

[nomofatum]

How bad do you think that affected the overall plants health and the quantity/quality of yeild when i harvest? Assumed the ph will be fixed in the next watering in 3-4 days from now ;/

Don't wait to fix the PH. Fix that now, the longer it goes the more damage. Those don't look very bad so minimal impact if you get it fixed now.

 

[DirtyMcCurdy]

How bad do you think that affected the overall plants health and the quantity/quality of yeild when i harvest? Assumed the ph will be fixed in the next watering in 3-4 days from now ;/

They will be fine. If you get the ph problem fixed soon

 

[Owais]

Don't wait to fix the PH. Fix that now, the longer it goes the more damage. Those don't look very bad so minimal impact if you get it fixed now.

What should i do? Water again with 6.5 ph water despite the soil still somehow wet? Wouldnt be that over watering and get myself in an another problem?