Quote Originally Posted by Zandor
That's a Hanna part number I think. Check www.hannainst.com and get the directions.
If it's the Hanna... as Zandor said, visit their site and download their instructions and manuals.

If you need more help, let me know and I'll scan my manuals and post them here. But please, please, try and download them... I will scan them, but if I can save those minutes of my life, all the better.

I'm almost 100% sure that your 800ppm solution is for calibration... The situation is the following:

You have your meter. Well, those meters get off-scale. So you need to "calibrate" them. You do that with a solution that has a specific value (800ppm in your case). You must try and get your meter in 'calibration' mode or something similar... then, you place the probe in your solution.

Many things can vary in this. My meter (Hanna) can be calibrated with one point, or two points. Two points is more precise. For a two point calibration, you would have, for example, (a) 800ppm solution and (b) 400ppm solution. (The 400 is made up, it's probably another value). The meter uses these two known, specific concentrations (ppm) for calibration.

Think of it this way, your meter doesn't know what it's reading... It's unsure if 500ppm is really 500 or it's 700ppm because it's off by 200. So, you tell your meter; "Look meter, I'm going to give you an EXACT 800ppm solution..." And the meter then calibrates its self to that 800ppm... now, all other measurements should be accurate.

In addition, meters can have 'automatic identification' of the solution, or manual. My meter for example, I can use the calibration solutions, and it will automatically know which solution I'm using. Some meters, you need to specify to it which solution you're using.

I hope this helps... and I hope I'm not blatantly wrong.

Best to you,

-turtle420