I tested by putting it in a container with water and let it sit while I ran the same test with my kit. PH was a little lower than I would have read the color but that’s probably me reading color wrong. The salt showed a little lower than my test kit but not enough that I would be concerned it’s not accurate.
So far VERY happy with it! Just hoping for a video on how to best test to make sure I’m doing it correctly
Anyone using a meter should have a couple of shot glasses for rinsing and calibrating, some demineralised or distilled water and the appropriate calibration and storage solutions. Most meters have a factory set point at 1413uS (micro Siemens). The conversion factor to ppm is complicated but 1413uS is below 1000ppm NaCl so if a meter is to be used as a serious measuring tool it needs to be calibrated at a point close a pool’s salt level, 3000ppm or higher. For salt testing ensure the meter is set to ‘salt’ with a conversion factor of 0.5.
The factory calibration point is probably not too bad if it is used to test solutions like tap water that are below 1000ppm but the variance in error increases as you move away from the set point. To get an idea of the scale of variance see the table of calibration points for the Com-100.
I use a HM Com-100 currently calibrated to 5000ppm NaCl. It reads to 10ppm but in reality it is only good to the nearest 100ppm. Meters need a little time to settle before taking a reading, wait until the value stops changing to record the result. I rinse it in tap water and then in distilled or demineralized water in a shot glass. Dry with kitchen towel and cap to store. Some meters say to add a drop of water into the cap so that the probe is stored moist environment but not wet. Cleaning is done with alcohol on a cotton tip, then rinse, dry and stir as normal. Never store a meter in distilled water. Regular recalibration is very important, my meter have drifted away from the previous calibration point by about 60ppm over the last few months.
But that is for a salt meter. I have the HM pH meter which is rinsed the same way but then stored in a storage solution, potassium chloride or KCl. I’ve never had much luck with pH meters, I only use my pH meter immediately after calibration. Most of the time it’s just stored away and in reality for general pool maintenance the phenol red and comparator is all that is needed. HM have a pH/TDS meter and recomended storing it upright in a potassium chloride solution so I would suggest the C-600 meter should be stored the same.
The pH standards should be made up as accurately as possible using distilled water but I would preference pre made standards over the salt sachets. Choose calibration solution either side of the testing range, for pool values 7 and 10 would be best. When calibrating use a small 20ml volume of calibration solution in a shot glass. Always discard the small portion of solution after calibration. Don’t be tempted to put it back to use the next time.
I use quality lab grade calibration solutions, a 3000ppm NaCl and 5000ppm NaCl which gives me confidence in the results. But nothing is perfect and mistakes can happen so is always a good idea to keep an eye on your SWG. The calibration point for my meter is user selectable but some meters have a set point, 5000ppm NaCl, 6440ppm NaCl or 12.88mS/cm (KCl).
I calibrate my meter then test a pool sample and verify the same pool sample with the chromate and silver nitrated test. From there I am essentially tracking the change in salt over time rather than recording absolute values. In theory a salt meters reading should always be slightly higher than the chromate silver nitrate drop test. Salt and temp is very handy for the CSI input which I record and monitor at every test.
Another thing that I have started doing is to prepare a reference solution with demineralized water and a little pool salt immediately after calibration. The reference solution is made to match the calibration solution using the meter. I use it every second test to keep an eye on my meters calibration without a constant need to use my expensive calibration solution.
| Device/Calibration | Hanna 3g/L | ACR 4000 dilution | ACR 5000 |
Com-100
ACR 5000* | 3060
+60 | 4080
+80 | 5000 |
Com-100
ACR 4000* | 3020
+20 | 4000 | 4880
-120 |
Com-100
Hanna 3g/L | 3000 | 3950
-50 | 4820
-180 |
* The ACR 5000ppm is the stock solution, ACR 4000 is a dilution.
Edit: I think the above results are very good. When calibrated to 3000ppm it was reading 180ppm low in the 5000ppm solution which is within the tolerance or error factor for the chromate silver nitrate test. My meter, the HM com-100, appears to preform best when calibrated to 5000ppm. A lot of the manufacturers instructions for use recommend to calibrate as close as practical to the sample value or in our case the SWG’s optimal operating level. Most of these meters have a pre set point close to normal tap water levels so its important to re-calibrate them to salt water pool levels.
I run water features all night to keep my pool cooler during the summer and thought it would be a less expensive way to test my pH — since I’m testing 3 times a week. I will still use my drop test weekly, & thought this might work the other times. But I would really like to watch some trusted videos to make sure I’m doing everything correctly. 
. I came here for the same reasons as OP.