City water ppm

My city water has a ppm of @280.

I want to build my nutes ppm to 1200

Should I build nutes to 1200 (reads 1480), or

Should I build nutes to 1000 (reads 1280)?

I have allowed city water to sit for 26 hours.

Thanks, Dale

normally you can exclude half the amount of ec or ppm as useless, so if ya have 280 140 can stay on top of the final ppm figure, however water quality is not good,much better to get a reverse osmosis filter or collect water from aircon units and de humidifiers, the other option is to use distilled water, this can become costly.

Thanks for the advice Misty!

Blue