New Grower You make the call

[midman4u]

Here are 3 leaves from 3 different plants.By just looking at the picture see if you can diagnose the problem

 

[namvet25]

cal-mag and phos def.

 

[Muddy]

I agree, cal/mag and P. But the real question is why? More than likely a pH issue.

 

[midman4u]

I have this issue with every grow.it is almost like clock work.I am positive it has to do with the soil i use.I dont have much of a selection here in the u.p. of michigan.The soil i get from my farm supply store is a good mix with lots of perlite and such.But i always have to add cal-mag at some point. i dont believe it is a ph issue since i test run off at the onset of the issue.