plants suffering - advice needed - urgent

hi all,


this is my second attempt at growing and i'm starting to experience the same kind of issues as i had with my first grow. i hope you can help me with this.

the pictures show my new plants which are 5 weeks since i cloned them and have received 2 weeks 125cfl and 3 weeks of mh. i grow in coco so i've been giving them Coco A & B (5 - 4 -3) Rhizotonic (root solution) - (0.6 - 0.2 - 0.6). the EC levels haven't been higher than 1.2. I have now stopped giving Rhizotonic and only giving A&B. humidity levels are around 50% and there is sufficient air intake and circulation. Temperatures peak at around 31 degrees celcius. there is obvious yellowing on the older leaves which is how my problems started with the plants i have in flower. i've taken the plants out of the pots and the roots look and smell nice. first sign of something wrong is when i noticed purple lines and leaf stems. as i understand that can also mean different things? also the growth has slowed down a bit.

the larger and totally yellow plants are the ones i have in flower (4 weeks) and as you can see they are pretty much dead. i've been giving them A&B and Cannaboost. EC levels have not been higher than 1.8.

i did discover yesterday that my ph meter is off and i tried to calibrate it without any success. i'm not sure that this is my problem as when i had my first plants in vegetation my ph meter was calibrated perfectly. is anybody using Hanna Instruments PH & EC meter HI 98130? the problem i have with calibrating is that it doesn't recognize the 7.01 buffer solution. as i can understand from the manual it should that automatically. when i put my meter into the 7.01 solution the meter shows me 8.45 and when i put it in the 4.01 solution it shows me 6.07. any advice on that?


id really appreciate any help you can give me. i'm sure you guys have ideas that i might not be able to think of


thank you!

i Use the hannah Checker 1 PH meter and i have small turning screws on the top to calibrate it. I dip it into the 7.01 solution and leave it in for the reading to stabalise and then readjust using the adjustment screws to change the display to 7.01. Then i wash the electrode in plain water and dip into the 4.01 and adjust in the same way.

I also use COCO and i feed constantly at an EC level of 1.5.

This looks like a ph lockout causing all sorts of problems for you.

I would personaly use a flush additive and make sure of your ph. If you dont trust your Ph meter then i would run out and get a little ph dropper test kit for now.

Flush with your ph'd water with flush additive then after you have done this i would then run 1.5 times the size of your pot of an EC of maybe 0.8.

Ph is crucial when you are growing in coco.

Get the dropper kit if you can and then wait until new growth comes out clean. When the new growth is clean and green start picking up your EC but i wouldnt run it higher than 1.5 for a while.

The ones that are experiencing the yellowing on a few leaves looks like N def so pick up a regular watering schedule with these. You will not get any change in the yellowing but the new growth should start coming out healthy again.

the ones which are seriously yellow you may have to cut your losses and start over.

With coco it is usually devoid of nutrients (no nutes) therefore you have to feed almost from the word go.

I usually start with a low EC of around 0.4 until i get some pale leaves and then begin to up it to 0.8 then i go to 1.2 then i get to 1.5 and stay there.

Hope this has helped somewhat to your problem.


J

thanks for your reply. it was a long time ago but i've been testing it out now with a new nutrient solution and also re-calibrated my ph meter and things seem to be going fine at the moment.

just wanted to ask a couple of things

how often do you water?
how much water do you give them? (i use 12,5 L pots, humidity in veg around 60% and 45-50% in flower, temperatures up to 30 Celsius)
do you go up to 1.5 EC levels when you put them on 12/12 or in veg already?


so far you have been a big help so thank you!