SULMILE AZ-86031 5 in 1 Water Quality Meter Dissolved Oxygen Tester PH Meter PH Conductivity Salinity Temperature Meter AZ86031 PH 4 PH7 PH10 Solutions & D.O. Electrolyte Included

I guess the sellers keep going out of business as this is my 4th review of this product on Amazon and I don't see previous reviews as I guess the original sellers are no longer on Amazon. So, to repeat myself, I used to do professional water sampling (10 years) of surface waters (lakes and streams), groundwater, and wastewater testing. Compared to the other devices on the market this is 40-50% cheaper and just as good (accurate and durable) in my opinion. The only downside to this device is getting data off of it as it does not have an SD card, USB port, or other means of getting your data onto a pc. I still gave it 5 stars because I currently use it for my backyard pond for water testing and it is overkill for that. The device held calibration for about a year with proper maintenance (cleaned probes with distilled water and kept them in storage solutions when not in use for extended periods).

This product does not calibrate and it's been in use for under 6 months. There is no information to contact the manufacturer or seller to remedy the problem.