Calcium deficiency??

Noticed this on the leaves of one of my plants, after doing a bit research I think it might be a calcium deficiency? Was just wondering if anyone could confirm this?

The plant is blueberry cheese auto in biobizz all mix soil, I have just been watering them with tapwater with some rhizotonic root stimulator. They are 2 and half weeks old, this is the only one it’s happened to. Any help would be much appreciated.

That is most likely caused by nutrient excess . Allmix is transplant mix and not intended for seeds/seedlings. You got a lot of calcium/lime in the "biobizz allmix". She will recover but don't add any nutrients at this stage.

For me, anything Biobizz, lacks Mg, which causes a magnesium deficiency, and it will happen right away especially when you are growing a heavily leaning Indica that has Afghani in her cross. So either add 3ml ca/mg+ to each 1 gallon of water or feed, or add 1/4 tsp Epsom salt to each 1 gallon of water or feed! Magnesium is like the 8th most abundant mineral in the earths crust, but in the Afghanistan region, it is the 2nd most abundant mineral in the earths crust. And where the plant ultimately evolved will always determine their basic needs! So, like I said, anything that has Afghani in its cross, will want / need, more magnesium to grow happy by default!