Review on VIVOSUN 3-in-1 Digital pH Meter: High Accuracy, ATC, 0-14.0 pH Range by Ruth Ward

The only thing this company is good at is making vibrating 6 inch fans. measured distilled water by weight to ensure the pH solution was accurate and also kept the water in a circulating tank to keep it at an accurate 77 degrees. The meter calibrates accurately to 6.86 but then registers 4.00 as 6.72 and 9.18 as 6.97 and keeps recalibrating all 3 solutions to 6.86.2 out of 3 products I've bought from them similar accuracy/consistency issues; 3rd is a fan and has no measurement. Still, the motors are dubiously weak and their vibration mechanisms slip at the extremes. Obstacle. I really like this company, in general I would say stay away.