Looks quite healthy. Worried about the variation in color on those leaves? It’s genetic and won’t pose a problem.
@KoolHandLuke , that is a riot, I nearly fell out of my chair!
@jumper
What you’re seeing is a magnesium deficiency. This can be caused by intense lighting, or if you’re using Reverse Osmosis water, and distilled. They have no minerals in it.
Experienced community members and expert staff will be better informed and more capable of providing a more informed answer.
COPY/PASTE the below list into your forum post.
Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)
- What strain, Seed bank, or bag seed
- Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
- Vessels: Pots, Grow beds, Buckets, Troths
- PH of Water, Solution, runoff (if Applicable)
- PPM/TDS or EC of nutrient solution if applicable
- Indoor or Outdoor
- Light system
- Temps; Day, Night
- Humidity; Day, Night
- Ventilation system; Yes, No, Size
- AC, Humidifier, De-humidifier,
- Co2; Yes, No
Always try to upload a clear picture of any issues you may have to allow the community to assist you.
Add anything else you feel would help us give you a most informed answer should be included. Feel free to elaborate, but short and to the point questions and facts will help us help you in a more efficient manner 
Thanks!
LOL That is what I was thinking…most often it seems a bit unclear but this appears to be a text book case of early magnesium def.
@Covertgrower nailed it… plant safe epsom salts is in order to make that a thing of the past.
Like @Cannabian mentioned epsom salt without ant scent added. I use 1tsp/gallon.
I am growing in Coco and have the same deficiency. I thought I was looking at my pictures for a second. Luckily I had read on another tread where @Covertgrower was having the same issue. He advised me to increase the amount of Epson salts, and I already see a big improvement in the new growth.
I had some issues, they seem to be resolved with the adjustment. It was only a few plants that had the issues, but nobody else is complaining since then. Think I got it.
I use distilled and always have to add Epsom Salts, and also a good (low N) Cal Mag.