here is exactly how i use mine. I use the bottle of distilled water that it came with (filled it with rodi because i used it all). put that water on the prism and fully cover the lens with water using the distilled dropper only. Eliminate the chance for cross contamination with saltwater. Do not use the dropper for s.w. the distilled water, and the meter should both be room temp. Hit the zero button. It should read 1.000. I then just use my normal dropper and suck the distilled off of the prism, and spray it on the floor, on my pantleg, wherever. Next, i fill and empty my s.w dropper a few times with tank water, to flush it and get a good sample. I then fill, and empty the prism, to flush any remaining distilled off of it. I then refill the s.w dropper, and fill the prism with s.w to be tested, just enough to cover the lens opening. Let it temperature adjust for 30 secs, and hit read. There is your measurement. I usually wait another 10 secs or so, amd read again, so to see if it stays the same. Yoy can then get another sw sample, and test again, if you want. When im done, i bring the meter to the sink, run water over it to rinse off any salt, dry it gently with whatever towels around, and put it away. I used this same method, but with the included 1.025 cal solution, and it tested 1.025 dead on. And this goes for BOTH mine, and works meters. I am fully happy and confident in them. They have been very consistent. So either ( no offense, im sure you're not the problem) you're doing something wrong, or this meter was dropped at some point, or is faulty in some way. Im sorry about that crappy customer service. That is a shame, because i do think it is a good product, and they should stand behind it, and they should WANT you to be able to use it. Good luck.
