deficiency or heat stress?

Hi all,
I have some yellowing on one of four plants. It started with discoloration on more then one, then i added some magnesium, but on this one it went further. I was reading about zinc deficiency, but i'm also watering with nutes that include micronutes(It looked similar to picture of zinc def. about a week or two ago). The problem seems to be only on tops closest to light. Its 400w hps in cool tube. I had it as close as 15cm or even closer at some times. But few days ago i moved it a bit higher. I didn't check ph runoff so far.. I was also wondering if it that is becouse of difference in temp at tops and roots. The room is at 22C

It is likely ph, I'm betting way too low probably low 5's upper 4's... Check it asap... Too low ph will lock out micro and macro nutrients regardless if you are feeding, the roots just wont function as they should if the ph is out of range. If you are in soil, from experience try to be around 7 or just below, anything less than 6.5 will start to show problems. Some plants are ultra sensitive to ph where you don't get much of a "sweet spot" range.

Ok thanks. I will check for pH asap. But it shouldnt be too low, as when i mixed the soil i also mixed dolomite lime in soil as it is supposed to neutrelize pH and keep it close to 7... The water i use has pH around 6.8 anyway and i didnt give a lot nutes so far, always below the amount it is stated on nutrients so it shouldnt be under 5..

Thanks for answer.

Back the light off

Im with bernie!! 15 cm???? Dude, NO.
Looks like Zn, mainly on new growth with banding appearance..

could be zinc. most likely a ph issue. your mico newts are hosed. water, water, feed.

ph nute water, water straight from tap. test tap water first.

a little swing in ph is good. the micro nutes are absorbed best at different levels.

It's light bleaching. Back the light off like Bernie said. It happens when the plant can't produce enough chlorophyll to keep up with photosynthesis.

light bleaching

You better do it soon, if it gets any worse it will be permanent. As I see it now, it has time to recover, but not if you don't raise that light.

Thanks for answers everyone!

So most of you say it is light bleaching.. I hope it is and i also assumed so. As i think i noticed that its gone on tops that aren't close to the light, and it appears to be just on those closest to light(I'm turning plants around so that all tops get as much light as posibble). But why would it occure only on this plant? It is all the same genetics. But sure every of them looks a bit different, one is even kinda defected since beginning, and some are much more streched then others. I use same soil for all plants, same water, i don't use tap water anymore, but i get it from rain collector. Our tap water is not really good for plants in my opinion. It seems that things are much better this season using rain water. And it's ph is around 6.8 + no chlorine and such stuff..

P.S. what size pots do you suggest for aprox. this size of lst'd plant? It's ca. 4weeks in flower, didn't note down the fllip date :/ They are too far away and it's a lot of unused space in the middle of 4 pots.I have 2x 20l, 1x 18, 1x i think 30l pot(didn't find smaller)..

So, again thanks everyone for help. I'll move the light further away in the "morning"

If they're all from seed but the same strain, you're looking at different phenotypes. Some strains/phenos can be more prone to it. I grew two of the same strain of OG before and one pheno was more sensitive to the light, so I had to move it to where it's not as bright. How big are the plants?

my plants are 1-4 inches away from my 400w hps,,but only one plant bleached some of the others just got burned

Rush56 said:

Hi all,
I have some yellowing on one of four plants. It started with discoloration on more then one, then i added some magnesium, but on this one it went further. I was reading about zinc deficiency, but i'm also watering with nutes that include micronutes(It looked similar to picture of zinc def. about a week or two ago). The problem seems to be only on tops closest to light. Its 400w hps in cool tube. I had it as close as 15cm or even closer at some times. But few days ago i moved it a bit higher. I didn't check ph runoff so far.. I was also wondering if it that is becouse of difference in temp at tops and roots. The room is at 22C

Click to expand...

If it was light bleaching it would be all over the affected leaves especially at the top and highest colas cloesest to the light and not just on the edges. The darker green veins on most of the leaves in the close up pic suggest to me that it's not light bleaching and is most likely either a PH problem or a nutrient deficency or both... I would move the lights up just incase it is light burn but I would also check the PH asap to make sure you don't have a lockout...

Light bleaching on a clone with PH issue... If this helps...

When i checked on them yesterday when the lights got on i think it looks much better now, since i moved the light for about 20cm or more from that plant. And the problem was only on the tops closest to the light...
If it will get worse again, then i really should check the ph.
P.S. Before last visit i turned my plant around again for ca. 180degress(2days ago). The tops that were bleached or whatever are now on the other side and not so close to light anymore. This are the tops i took photo of and now they seem darker and the yellowing seems to dissapear to some degree. Also the tops from that plant, which are currently exposed to the light mostly didn't show any such signs, but they are double the distance away from light now.
I hope it really is just light bleaching.
And the reason why i was trying to get it as close as posibble is to get hard buds, becouse last two indoor seasons i had fluffy buds, but however it was not just becouse being too far from light, but i also had some defeciencies.
Anyway thanks for explaining about phenotypes, i understand it now.

Thanks everyone for help again!

p.s. someone asked how big the plants are. I use lst training to keep them as low as posibble and to keep most tops at same height for best light penetration. I was vegging for about a month. I really can only guess how big they are, becouse that information wasn't really needed so far and i didn't measure. In height they must be mostly around 40-50cm if not less. How wide they are, you can see on a picture i posted. Some are a little lower and less streched some are a bit bigger and more streched.

Hey rush! A lil warning since you're new here, I figured I'd letcha know there's a whole lot of disinformation on RIU bro ...lots, peeps will offer you solutions and don't know spit about growing ......LOL One look and anybody with a couple grows under their belts should have been telling you that the lights are too close, just by looking at the plant ....a pH issue? hahaha ..where? I'll add that a deficiency doesn't always show up the same way, I've seen plants with a calcium def. range from having rusty spots on the leaves to just having twisted new growth!
Listening to some of the peeps here is like asking for more trouble in the end!

P.S. Check to make sure the issue isn't an enviromental one first ....it's the easiest to fix and it'll save ya some headaches! Good luck
-sym