Yellow spots

Hello sorry for this post, my supreme grapes have yellow spot, and i don't know what the problem is.

veg Tent 35x35x60cm

Quantum board 50w lm301b

Pot 3L

3 weeks since sprout

I started plagron alga grow 2 watering ago with plagron power Roots.

Soil plagron light mix.

Ph water 6.5View attachment PSX_20210824_191534.jpg

Magnesium deficiency

jfarrismu said:

Magnesium deficiency

Click to expand...

Ok thanks, i will give her a little bit of calmag