Deficiency?

[Camboja]

Start of 5th Week of Bloom

Hey guys! I'm growing in a 1x1x2m grow box, using Carolina Soil, 70% Sphagno Peat + 30% Vermiculite + Limestone​, as a substrate and fertilizing with the High Bloom (A+B) line from High Nutrients. Mineral fertilizer

Currently, I'm watering with a pH of 6.1 and PPM of 616, with a PPFD of 1000 in the upper parts. Im using a led 24w bar from ali express. The temperature is stabilized at 25°C and the humidity at 60%, maintaining a good VPD for this phase.

In the last few days, I've noticed yellowing in the older leaves and some burned edges, possibly indicating a deficiency of potassium (K) and magnesium (Mg). I'm adjusting the PPM to 900-1000 and supplementing with magnesium sulfate to correct it.

Am I sure? Here are the girls' photos
The buds are starting to get bigger, and I'm monitoring the plants' response. If anyone has any suggestions

 

[GrowNinja]

Hey Camboja !

Looks like potassium deficiency, according to Plant Doctor from the site. Caracteristic Brown ---> Yellow--->Green in the leaf. If you are giving it Nutrients, then the plant is not taking it so it could be a potential PH problem.

Plant looks a bit stunted to be in 5th Bloom as well, I'm leaning towards PH problem

Let's see what the more experienced guys think. Good Luck !

 

[Rwise]

She is eating her leaves for the nutes in them, 6.1 PH is vary much low (and causes lock out) for soil and flowers, try 6.5-6.8.

 

[Camboja]

Du u think im puting low ppm on the plant? Iam think thats the problems, because the plant on this age is taking more nuts according to my table.

 

[Bluey]

Those leaves in the first 2 pics looks like that part of the plant is dying. Did you supercrop or break any branches?

The 3rd pic the new growth looks pretty good but too light in color and to be honest you look like you are in the first week of flower and not the 5th.

Your pH is way too low but I see other issues too.

If all you are using is a 24watt LED light bar the lower leaves with the die back are dying because they are not getting enough light.

Shows us a pic of your light setup relative to the top of the plant.

 

[Camboja]

I apologize. Actually my LED is R$240w.Thanks for the answers, don't you think I'm giving the plants too little food?

 

[Bluey]

Under a 24w light no, probably too much.
Under a 240W light yes, too little. In the 5th week you should be lots more all else being ideal. We try and feed the most we can without issues and monitor that. I use the EC measurement scale and found mostly plants when mature happiest with a Max nute mix of around 1.6 to 1.9 but some will take more which is in the 800 to 950 range on the 500 ppm scale. My sativas get problems above 800 yet I've seen other strains thrive at 1000

 

[GrowNinja]

I don't know really. PPM is a bit advanced for me. I'm just learning how plant changes and evolves depending on the basic principles: Soil,, Air, Water, PH, Nutrients, Light, Humidity.
PPM, EC, PPFD, VPD and others, are concepts that escape my knowledge for now.