Willie,

Step by step... we're trying... we'll get there

Your 800ppm solution, you use to calibrate your meter... I'm on my 1st grow, but I would calibrate the meter @ the start of everything, and every 1 month. Let's wait for Zandor's input on this.... more experience.

When do you use your meter...

Ok, after/while mixing your stuff. Let's say you want to fill your rez (reservoir).

1. Water into the rez
2. Use your meter to check your water's ppm (if it's tap water, it will have some 'stuff' in it... 200, 320 ppm... depends where you live)
3. Add your nutrients one by one, according to their instructions... At any and all times, you can now use your meter to actually "see" the exact ppm amounts you're adding of your nutes...

4. When you finish mixing everything, you can check (with the meter) your solution's ppm... There... General Hydroponics (GH) has a chart that I plan to use, as per Zandor's advice. It has the ppm levels plants should have for every week of their lives.

After you're running your solution through your plants, you can check (with your meter) the ppm to know what your plants have consumed. So, if you mixed everything and had 800ppm, and after 4 days your plants have consumed (example) 2 gallons of water and... your reading is now @ 550 ppm... soooo.... your plants have taken up the difference in ppm.

Willie, I'm on my 1st grow, and, my meter, I've actually never plugged it in yet. I hope this helps. Please read all replies, as I may be wrong in some of the things I said (C'mon guys! I can't be wrong in everything!!!).

Keep posting, and, slowly but surely, you'll get all your questions answered.

-turtle420