Any advice??

I think these answers nailed it. What you need to do to fix immediately without causing further damage is a light foliar spray of epsom salt. I’d run it through Ai to see the concentration given the nutrients you use. Don’t forget water on leaves and intense light don’t mix.

From what I can see: -The leaves show interveinal chlorosis (lighter green or yellowing between veins) while the veins remain darker. -The newer growth looks a bit twisted and lighter green, which can indicate a micronutrient issue rather than nitrogen. -The leaf edges and general color suggest the plant is otherwise healthy, so it’s not severe toxicity or overwatering. Given your setup (Plagron Batmix + Lightmix, BioBizz Ca, Greenhouse BioGrow nutrients), the most likely issue is: Magnesium deficiency Why: -Batmix and Lightmix both have nutrients, but the combination can cause high Ca and K levels, which can lock out Mg. -The pattern of lightening between veins on older leaves is classic for Mg deficiency. -BioBizz Ca (Calcium supplement) can make this worse if Mg isn’t supplemented. ✅ What to do: Add magnesium: Use a Cal-Mag supplement that includes magnesium, not just calcium, or Add Epsom salts (magnesium sulfate) at 0.5–1 g/L (about ¼–½ tsp per liter) in your next watering. Do this once, then again in 5–7 days if symptoms persist. Check pH: For soil, keep pH around 6.2–6.5. If your pH drifts higher, Mg absorption drops sharply. Avoid excess calcium: If you’re using BioBizz Ca often, reduce frequency — too much Ca locks out Mg and K. Monitor new growth: The damage won’t reverse on old leaves, but new leaves should come in evenly green within a week or two. Hope that helps! 😘

The robust growth is 95% because of the plant's genetics, not the products or the medium. What we contribute is more akin to not stepping on our own dicks or flaps. You can have plants in even better health and might not grow as fast. Keep'em healthy/happy and let the chips fall where they may. Less likely to be Mg-def symptoms. Those don't become visible until 4-6 weeks after the deficiency starts inside the plant's age throws a wrench in that diagnosis.. plus, mg-deficience is interveinal chlorosis with rusty spots.. not without rusty spots.... but hey, if that's how it progresses, i'll eat crow and say i'm wrong. You do have some interveinal chlorosis, but it clearly hasn't held your plant back too much as it's growing quickly. I'd make sure the pH isn't whacky and that at least some part of your fertilizer or soil is providing micronutrients - Fe, Mn, Zn can all cause interveinal chlorosis. It may even just be a little variegation on early leaves and the plant will grow out of the blemishes. I'd be patient and see how it progresses a bit more before any reaction to the interveinal chlorosis.

CalMag issue top - Mg lock bot - likely Ca lock do u know ur water ppm or u use CalMag bs other ppl using it ?

hey 👋 There is clearly an early stage of magnesium deficiency, which is causing discoloration between the leaf veins. But looking at your diary, I don't think the problem is due to your fertilization; the most likely cause is a problem with the pH of your water: aim for between 6.2 and 6.5. If the pH is correct, then it must be an excess of P, which blocks the Mg; in this case, reduce your Biogrow to 2ml/L, and not at every watering. You can fix that easily and quickly 👌