Indoor exodus cheese under 600watt hps

[AfrikanSun]

Hi Hunters

 

Busying with an exodus cheese grow currently on day 28 of flower. 

 

I grow under 600watt hps bulbs using 10l pots with coco perlite 90/10 soil. 

My tap ec is 0.8 (contains calmag) and ph 7.6. I'm currently feeding with short flower powder feed. I use phosphoric acid to lower ph. I add amino mix to my rez to help with the uptake of cal. 

 

The phosphoric acid I use is 85% and food grade. I dilute that 3l acid with 6l water making 9l. To drop my ph to 5.8 I use 400ml of that mix. 

 

Currently running an ec of 1.4. And ph of 5.9

 

I was using nitric acid last week but changed to phosphoric due to tips burn on leaves. Because my ex is in check I assumed it was nitrogen to city due to the excess nitrogen. 

 

Please help.... 

 

 

 

 

[Chefblake420]

Wait what's the problem here? Your summary is very technical but I was with you till the last paragraph. They are nutrient burnt? They don't look like it. Maybe I misunderstood. These plants are healthy aren't they?

[AfrikanSun]

Thanks for the feedback @chefblake420

 

the tips of the leaf are burnt, curling down and very dark green, which leads me to believe that its nitrogen toxicity. the light in the pictures doesn’t show the tips very well. 

I don’t think it was due to high ec as i check my runoff and it was the same ec (1.4) or 0.1 lower which according to my research is ideal.

I was reading Francos articles on ph and i think a combination of needing to use alot of nitric acid to drop my ph from 7.6 to 5.8 and running a ph of 5.8 making the nitrogen more readily available. That is what gradually leads to the nitrogen toxicity in week 4 of flower. Since then i have been using the phosphoric acid and haven’t seen it get any worse.

if you look at the close up selfie of the bud you can see the tip burn starting and a few of the leave curling down.

im just confused of the tip burn and assume it’s the nitrogen toxicity but i can be wrong.

Once the plant has the tip burn does it stop growing and herm or will it be fine till week 8 in your experience.

Thanks in advance.

 

 

[AfrikanSun]

@chefblake420 the pitures just above your comment in this post show it better than mine. the leaf is curled down and the tip is burnt. my exodus cheese has the same signs.