hydro ppm nute question

Hey everyone

So I got a couple 5 gal dwc setup and I have some questions...

I dont have ro water so im starting at around 400 ppm...
I have no idea whats in the water to begin with...

that being said, when I start adding nutes do I adjust for the tap ppm?

For instance, my plants are 2 weeks old, getting some nice roots...

I added some cannastart so I know they have a little bit of nutes but now
they are getting a little yellow...ph is fine 5.9...

so do I add the tap ppm + nutes ppm, or do I disregard the taps ppm?

right now with added cannastart and my horrible water im at about 600 ppm witch sounds pretty high for week 2...

I would get a ro filter but I read they waste a shitload of water and I got 8 5 gal buckets so it didnt seem very practical...

I more or less disregard the ppm of my water when I feed. Your 600 ppm is actually 200 ppm of plant food.