I think u need CalMag
Maybe u got an PH Problem in ur Soil. U need to Test ur Drain for more Information.
I use biobizz too and its looks like if u PH adjust ur water permanent ur PH goes under 6 and than the plants cant absorb CalMag
I dont adjust my PH no more in negative.
I got an 8 PH,
after i put all biobizz nutrients inside the Water got 6,5 PH.
When i only give water, i let the water 6 - 24h stand in the room in the Tank to dechlorinate. I dont adjust PH anymore in the normal water too.