Ph low?

Reminds more like lockout or root issue. Cause either overfeeding or wrong watering habbits, that could lead to pot ph drift. In diary plants look too heavy stripped and light is just bombarding them, lift it higher. You use dutch buckets, when plant would be ready for watering , i would just pull it out from pot, if all roots are brown - you have an answer. At same time you can check how to measure and collect run off. Its values will tell you even more ;))))