Strange leaf problems - discolouration

[Oilersfan]

Hello,

New to the forums. Been lurking here a year or so but decided to join. Doing my fourth grow right now and having some issues.

Strain: Chocolate mint OG (Humbolt seeds)

Setup: 30"x30"x5' high tent. 200w LED quantum board light. Ventilated w/ carbon Filter.

Pot: 10 Gal fabric pot (about 8 gal of dirt) Happy frog soil, Ocean forest Soil, Coco, pearlite. Initial pot was just Happy Frog soil.

Enviro: 21-25 degrees celcius. 50-60% humidity

Water: reverse osmosis bottled water (1 -1.5 litres per watering)

Nutes: Gaia green all purpose during Veg, Gaia green Powerbloom during flower.


So, I moved my plant into the larger pot about 2.5 weeks ago. Everything was fine at the time. Plant looked healthy but the leaves gradually started to change color and the oldest larger leaves started to get brown/red a bit. I think it may be slightly stunted or shocked from the transplant into the richer dirt.

The new growth is nice an green (also pictured).

I checked my water PH and the run-off PH and it seems to be fine in the 6.2-6.4 range

I had my light about 20-24" above the plant but I have since moved it as high as I can get it in the tent (about 30" above the plant now).

I haven't added nutes yet. I usually rely on the dirt for the first bit and then add nutes around week 2-3 of veg. I will be adding them next water.

No bugs present.

I added a small amount of Cal-mag in my last water at the advice of a guy at the store I buy some of my equipment at. I had heard its a good idea to use a bit of Cal-mag if you have Coco in your grow or use purified water. My first grow I just used declorinated tap water and it seemed to be fine but I have really hard water in my area so I decided to start using purified instead and it seemed to be ok on my last two grows.


Anyone have any advice? Am I on the right track? Was it just the light distance and Cal mag issue?

[ChadWestport]

coco does require more cal-mag because of how it uses ions within the medium compared to soil. It's good that your new growth is nice and green. What that tells us, with the upper part being fine but the lower leaves having the issue, is that the problem is likely due to a mobile nutrient.

There is mobile and immobile and mobile ones tend to be pulled from lower leaves when it is needed in higher demand by the upper leaves. So start your search with learning the mobile vs immobile nutrients. That will narrow the possibilities. Many problems look similar, but possibly explore a magnesium deficiency. Horticultural epson salt might help. The conditions you describe are all on point.