Cal Mag issue?

I suspect a cal mag issue but I'm looking for confirmation. Today is day 1 of week 6 of veg fwiw.

Could try flushing soil then feed regular ppm next watering. Might be salt buildup but I don't know what you schedual is. So just a shot in the dark.

Southernontariogrower said:

Could try flushing soil then feed regular ppm next watering. Might be salt buildup but I don't know what you schedual is. So just a shot in the dark.

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Maybe I'll just use plain water for the next few waterings? I don't usually measure ppm and don't have a meter, unfortunately. I'm currently using grow big following the light feeding schedule.