Question about Fox farm

Some question about fox fram, it may so stupid but I really want to figure out, thanks everybody. As I upload pictures marked.
1. ppm means tds?
2. Requires 420-560 ppm of fertilizer, is it also labeled twice a week, is it 420-520 ppm each time, or is (420-520)/2 ppm fertilizer used in a week?

Yes ppm is TDS.
Each feeding with that PPM level, according to their chart.
User experiences may vary.

Should be an online chart for Fox farm.......

Chip Green said:

Yes ppm is TDS.
Each feeding with that PPM level, according to their chart.
User experiences may vary.

Click to expand...

Yes but EC is a more accurate way to measure what's actually happening at the root zone.

SchmoeJoe said:

Yes but EC is a more accurate way to measure what's actually happening at the root zone.

Click to expand...

I agree. With PPMs you need to know which scale you are using, 500 or 700.
http://www.just4growers.com/stream/plant-nutrition-and-growth-enhancers/nutrient-strength-ec,-ppms-and-tds-explained.aspx

Ths guy