What is the optimal ppm range?

[Android]

I am following the feeding schedule for 2-part nutes from BPN in my aeroponic setup.
The res gets a water change every week
Plants are in 3rd week of bloom and fully grown now (about 3-4 feet tall)
Here are the readings I am getting off my PPM meter after the water change:

day1: ~1600 ppm
day2: ~1400 ppm
day3: ~1100 ppm
day4: ~900 ppm - once it falls below 1000ppm, I add a half of recommended dose
day5: 1500 ppm
day6: 1300 ppm
day7: 1100 ppm

The plants are well and not showing any signs of deficiency
Ph stays within 5.5-6.1
I am using RO/DI water as base
The strain is Kandy Kush

Does this look alright to you? Please comment

Another question: Is there anything in ppm data dynamics that would tell me the time has come to harvest?
Would plants stop using as many nutes as they do now when that happens, or no?

Thank you

 

[Blue Planet Nutrients]

The only way to tell if a plant is ready to harvest is by the color of the trichomes
For plants well out of the seedling stage with a well developed root system, the ideal ppm range is between 1200 and 1600. Each strain is different as to how much food they can take. What the solution contains is more important than ppm. For example lowering N and upping K and P during flower. the ppm may be the same as during veg but the nute solution is quite different.

 

[Android]

Thanks, Corey! Looks like I am doing it right.

When ppm falls below 1000 on the fourth day, I add a half of what I normally do of Bloom and Bloom Booster, but don't add any Grow at all. I like the fact that you can tell how much Grow is still in the solution by looking at the color of water - Grow has a very distinct color and it is easy to eyeball how much of it is still there (while Bloom is almost transparent)
I absolutely love your nutes! You are the man