KISS Method with RO water ?

So I've been doing the Kiss method with Ro water. I'm about 4 weeks and 4 days old. I've been having some issues:

Purple stems, steams feeling real weak. Leaves have been twisting upward. Dark brown spots on middle fan leave. The first set of leaves ( round ones) have already fell to the coco.

I was feeding with 1/4 Mb and 1 ml Calimagic every feed, under 370 PPM 6.0 PH

I did a flush yesterday, first reading before flush was 5.9 PH and 1770 PPM!

I did a flush with 1/4 nutes and 2ml Calimagic 330 PPm 6.2 PH yesterday, Because I thought Calicium and mag was best uptaked at that PH..

Now my readings were at
6.2 PH 400 PPM

Lights just turned on and she looks a little droopy.

Am I doing the KISS method wrong? I totally make a rookie mistake and didn't account for using RO water /:

 

I swtiched to tap (300-370ppm) and plants are very happy. (1 ml of ma - per gallon tap)