What is the difference between the WaterGuru SENSE S2 and the WaterGuru SENSE S3?

WaterGuru SENSE S2

• Alkaline battery powered
• 4 "C" cell batteries included in the box
• C5 cassette included in the box
• C5 cassette measures FC, pH, CYA, TA and CH daily
• Compatible with C2, C5, C2+ and C5+ cassettes

WaterGuru SENSE S3

• Integrated Li-Ion battery charged by the solar panel on the top cover;  USB C port for charging using a USB C cable and USB Charging block (USB C cable and USB Charging block not included)
• C5+ cassette included in the box
• C5+ cassette measures FC, pH, CYA, TA and CH daily
• C5+ has New TA, CH pads and an improved manufacturing process for pH and CYA pads
• Compatible with C2, C5, C2+ and C5+ cassettes
• Improved electronics in the cassette holder for greater reliability