Kali List - leafs yellowing, help

Hi. First, I want to say I've been searching hard for a solution but didn't find anything useful. Secondly, I've already posted in 3 forums about this problem, but I still have not found the cause of the problem.

The problem is only with the upper leafs which are getting yellow. The strain is Kali Mist. Here are some pics (Day 42):


Also, one pic showing the general look of the plants (Day 42):

The conditions:
The light (400W MH) is 2 feet away from the plants.
I don't know the Ph as I don't have a Ph meter.
Temperature / humidity:
Day: 67-75F / 48-56%
Night: 60-66F / 48-56%

The problem first occurred about 20 days after planting the seeds and a few days after transplanting in bigger pots with new different soil.
At this time I didn't use any fertilizers, only plain tap water.
At day 33 I started with Bio-Grow and Bio-Bloom (slightly less than the recommended dose).
I use Bio-Bloom because I was advised that the problem is Phosphorus deficiency.

It seems the problem is getting worse or at least it's not getting any better. 3 weeks after the problem first occurred I don't have a clue what is causing this...

Any ideas? Please help, I really need some advise.

Thanks.

interesting.... leaves turning yellow that arent on the bottom...

well, first thing you should do is get a pH kit from the local pet store, costs 10 bucks max, a simple vial + eyedropper bottle full of a colored liquid. another option to buy while there is a pH buffer, usually called simply 6.5 or 7.0 buffer. i bought the 6.5 one and have never regretted it. i use it every feeding, and my ph stays around 6.5-6.8, and since buying that, i havent checked my pH in months really becuase it never varies.

once your PH is ok, then you know its not a lockout causing this (meaning the nutrients are there, but the pH error makes the plant not be able to absorb it), after that well your options are to up the nutes.

its NOT overfeeding/overferting. chances are its a micro nute deficiency, could iron, zinc, magnesium, but the exact nute doesnt really matter, most micro nute bottles have a large variety of nutes, so if your missing one, your gonna end up adding all of them anyways. something else i got at the pet store was a bottle of micro nutes, made for plants in a fish tank, it contains 0-0-0 NPK, and around 15 micro nutrients, already dissolved in water. its awesome. since i bought that, ive never had a micro nute deficiency, its safe for fish to swim in, so i figure its safe for humans, either way i stop all nutes 2 weeks before harvest, ive never noticed a fish-tank taste in my herbs. that bottle can cost ya up to 20 bucks, but worth every penny.

if your on a limited budget, forget the pH kit. get the micronutes bottles, and the bottle of pH6.5 buffer. that way ya know your plants are being well fed, and the pH will not go haywire on ya.

im not sure id up the nitrogen a bit too, the bottom of the plant looks perfect. either way, ya have a nice grow going, and shouldnt get discouraged.

"i use bio-bloom becuase i was advised the problem is phosphorus deficiency" yea maybe, probably not, either way, id keep feeding it to them, at 1/4th strength. but tahts just me, i like giving them N+P+K and all micro nutes from start to finish, i just vary the ratios, but they always have each element.

oh, and + rep for being kinda new yet still knowing to take a ton of pics, that arent blurry, or fucked up cuz of the HID lighting, and a good explanation of your issue.

(most people just write "uhhh i see yellow, plz help")

........................................magnesium def i think, check what i sent you to make sure

my guess would be MG def and yeah as ^ suggested just add some micronutes and try to PH around 6.5

I've never used BioBizz products before, so I went to their site to learn a bit more about the product. I'm seeing that their Gro line's NPK is 2.8 - 0.2 - 6.6 and they claim to include over 70 trace elements. You also mentioned seeing this problem about 20 days after transplanting into new potting mix. 20 days seems about right for the plant to use up what's in the soil so it's probably the fertilizer that's causing the problem.

Before researching BioBizz I was thinking either over or under fed with a slightly bias towards over feeding because of how dark green the bottom leaves are. Now knowing what they put in it, I'm leaning even more towards over feeding P. I'm doubting it's the trace elements since your feeding tap water and their product has trace elements. Also I don't think YOU over feed the plants. I think the strain, plus the soil, and the quality of the ingredients just didn't mix well and the roots had a hard time getting what it needed.

Try a week of RO water with no nutrients. Then start back up with your feeding at the recommended feeding rates. That should help with PH, salt build up, and allow you to monitor the new growth.

Overall though I think your doing fine. A lot of my plants will suffer from something. Especially when it's a new strain or I'm testing a new line of nutrients. Its all part of the game of dialing things in. Your doing good and on track for a great harvest.

Thanks a lot for the responses.

Anyway, the problem is getting worse mostly in one of the plants. Here are some new pics (Day 46):


...and another one:


Maybe it's time to say I have two more plants (usually I get them away to make better pics of the Kali Mists):
1 x Seedsman Big Bud (Regular) - I think it's a male, but I'll wait a bit more to be sure.
1 x WOS Afghan Kush (Feminized) - Which has already shown female sex signs.

They seem to be unaffected from the problem. Here is a pic of the Afghan Kush:

The Kali Mists are in soil which is 100% from the local shop. Afghan Kush and Big Bud are in around 50% soil from the shop and around 50% random soil from the yard.

I have to water the plants today and I'm not sure if I should use nutes and how much...

I hope to buy a decent Ph meter in a week. I think to switch to flowering in 1-2 days.

What do you think?

Thanks.

Hi. I finally have a PH Meter (color strips). I tested the runoff water from the last watering and here is the result:
View attachment 2159467
I think it's slightly above 7 as the liquid seems to have some green in it. Is this ok?

I tested the tap water and it's around 8 Ph.
There is a spring nearby and the water from it seems to be around 7 Ph.
Do you think it's a good idea to water the plants with the spring water as it's with lower Ph compared to the tap water?

Thanks.

By the way the plants look ok. I'll upload some pics tonight as now they are in the dark period.

looks exceptionally healthy

Hi. Here is a new pic of the plants (Day 7 Flowering):

They seem to be droopy, so I watered after making the pic. Right after watering the leafs get even droopier. Is that normal?
Usually on the next day after the watering they look fine. I watered on the 4-th day after the last watering.

Thanks.