New Grower Why my autoflowers always show over N signs with 4 weeks?

[mmoloch]

I'm in my second grow and my autoflowers always show signs of over nitrogen when they have 4 weeks (without feeding them!)


HPS400w Gro&Flo with cooltube 18/6
Biobizz Light Mix + 30% perlite + 3 tablespoon humus/7L
Seven different strains had the same problem




First Grow


Temps with light 25/30ºc - 45/55% RH
Temps without light 15/20ºc - 65/75% RH
Tap water 260 PPM pH 8.0 rested for 24 hours and adjusted to pH 6.0/6.5 with lime using GH drops


Pics first grow

As u can see, they are with a very dark green and the tips of the leaves are curling like claws... I've read that over heat makes the plants eat more nitrogen so I did several changes before starting the second grow, duplicated the in/outtake of the Cooltube and began to mix tap water with bottled water...




Second Grow


Temps with light 20/24ºc - 35/45% RH
Temps without light 12/18ºc - 45/55% RH
Tap water mixed with bottled water 100/120 PPM pH 7.0 rested for 24 hours and adjusted to pH 6.3/6.6 with Bionova PH- using HM Digital pH-80




This winter the cold has been very dry, so when I saw the first signs of over N increased the intake...


Second Grow with more intake


Temps with light 20/24ºc - 44/54% RH
Temps without light 12/18ºc - 48/58% RH


Pics second grow

Auto Skunk Mas

Auto Afghan Mass

Auto Skunk 47

As u can see, the 3 plants already have a dark green and the tips of the leaves are curling like claws, on my first grow could not identify the problem and it took me a while to flush, this second grow flushed when I saw the first signs of over N and tested the run off water:


Run off water of the most affected plant (Auto Skunk Mass) - 850 PPM pH 6.4
Run off water of the little affected plant (Auto Afghan Mass) - 900 PPM pH 6.3
Run off water of the plant that is not yet affected (Auto Skunk 47) - 875 PPM pH 6.7






Why my autoflowers always show over N signs with 4 weeks?

 

[mmoloch]

... nothing?... nada?... 0... no one makes an idea of what can cause this over N problem?

 

[elby]

If you are not feeding them then the N toxicity can only be down to the Biobizz Light...

 

[jackmc]

Hi mmoloch, I can't answer your question but to me the plants look great. Does anything else happen to the plants when this deficiency shows up? If it's a serious issue I'd think you'd see it through out the entire plant. Hopefully one of the autoflower gurus will have a better answer for you. Try the Live Help thread if you don't hear from anyone else. Peace

 

[blue]

I think most will have trouble seeing an over N problem in the last set of photos! (definately got it in the first set)
The leaves are not particularly dark green or clawing down on this one.

I would guess if there were an N problem it would be down to either too much feed or an addition that has extra N in it (for example calmag)

N overdose picture

The bottom 2.

The easiest way to sort out an N overdose is to cut back on the feed until the leaves stop clawing down and start looking nornal

Hope this helps

Blue ^_^

Edit: Cold night temps and overwatering could make them look like that too.
Double Edit: I'd be surprized if biobizz lightmix gave you any tox. (a dodgy batch would be extremely rare)

 

[blue]

Hey MM - I'm gonna see if i can get wonderful Waira to take a look for you! I'm a little stumped if you're not feeding them and i just can't see biobizz light doing that! My problems were at the other end of the scale with light mix (underfeed)

Hang tight, I'll leave Waira a message to see if he can poke his head in for you.

Best
Blue ^_^

 

[elby]

Double Edit: I'd be surprized if biobizz lightmix gave you any tox. (a dodgy batch would be extremely rare)

Totally agree but it's either that, humus, perlite or the water and I can't see it being any of the last three Too little humus to make a difference, the perlite is inert and the water is... well, just water.

 

[blue]

Yeah elby - agree 100%

Can't be perlite, can't be water, couldn't find anything on Humus being N rich.
It's a stumper!

I imagine Waira will have the answer for us! I'm curious to wait for it!

 

[Waira]

:tiphat: mmo'- I gotta say, this is very damn odd,... have we accounted for all possible sources of N? --for example, some of the Ca-Mg supplements, Fe supp's, etc., have some N in the formulations,.. and zero feeding so far, right?... even if you did, Biobizz is very mild,... Biobizz light... seems I saw something going on with another person recently,... I'll have to dig it up if I can recall where,... they too had some nute burn issues..(?)... anyway, point is, I thought they might have used the All-Mix, which is pre-loaded with fert's already, but they said no,... :dunno: without a doubt, that's N-tox, and the yellow/brown tips are a more general sign of nute' burn,... All the more puzzling, your pH's and water ppm's are just fine... temp's not an issue either,... Huh! -only thing I can think of is a factory error in packaging or production- scratch that!- still doesn't make sense because if it were so, these symptoms would have shown up right away when they were seedlings, at their most sensitive time.... clearly, it's better this 2nd grow, but seeing the symptoms appear this late in growth makes me really grind! ... nobody else is messing with your girls, are they, good intentions or not..? Sorry mate, but none of this adds up,... try a different medium brand next time, maybe get a process of elimination going here,...