Hey mack 10. Welcome.
I mix my tap water with ro so i get to 0.3
Where i am there is an good amount of ca and mg in the water. SO it will have a good ph stability. Wich doesn't mean that the plants can use this form of
calmg it the tap. They can, but alot slower.
After 0.3 i add the base nutrients. Strictly base get's me at 1.3-1.4 early bloom 1.5-1.7 mid and 1.7-1.9 late. Last week veg ec 1.3 for flushing. I flush the medium one week before harvest till the drain comes out wih 1.3 veg.
Metrop is a good fert. Doesn't contain the best chelates, but if handled right it will produce good flowers.