Can anybody advise on why some leaves here are showing dark markings? Please help

[sandyinlondon]

This plant is a little over 2 months old and seems healthy. last few days it is showing strange dark markings on the leaf edges - please see picture attached here.

Can any knowledgeable person (I am a newbie and this is my first grow) recognise what is going on, and advise if I need to do anything differently?

Plant is Lemon Haze strain grown from seed in soil/pearlite mix, with watering using half strength Canna Coca A +B nutrient, living in a row tent at 21 C and 65% RH under a Philzon LED grow light PH D-6 model number.

[Cloud]

Looks like a ph problem and possible nute lockout from it. Give a good flushing and see what runoff ph is and ppm.

[sandyinlondon]

Hi Cloud

Thanks for quick reply - may I ask if flushing means watering with pure water (tap water, no nutrients) and then testing runout water for pH ..I have a pH meter so will do that if the process is confirmed

Not sure what is meant by ppm...what is measured and how is it done?

[sandyinlondon]

Hi again cloud
Ok...I looked up ppm and know what it is now - TTS meter now ordered

I checked the pH of my tap water...about 7.5 I then poured a pint of this onto the soild and then pH tested the runoff which was about 7. Is this OK. ? Now what do I do

[SoOrbudgal]

Allow them to dry and lift the pot so you know when they need water.