Apera Instruments 5031 TDS Pen Tester – Drinking Water & RO System Meter

Apera Instruments 5031 TDS Pen Tester

The Apera 5031 is a pocket-size TDS (Total Dissolved Solids) pen tester built for fast, reliable water purity checks at home, in the lab, or in the field. Part of the Eco Series, it features a dedicated fixed TDS sensor optimized for rapid stabilization and accurate readings — ideal for verifying drinking water quality, monitoring reverse osmosis (RO) system output, and checking general water purity. At just 6 oz, it slips into any pocket or water testing kit for instant, on-the-spot TDS measurement.

Why Choose the Apera 5031?

Dedicated TDS Sensor — fixed, parameter-specific probe delivers fast stabilization and accurate total dissolved solids readings without cross-parameter interference
Ultra-Compact & Lightweight — 6 oz; fits in any pocket, under-sink kit, or field bag for true on-the-go testing
Simple Point-and-Read Operation — no complex menus; instant TDS verification for homeowners, RO system users, and field technicians
Cost-Effective — professional-grade TDS accuracy at an economical price; no expensive lab instrument required
Easy Maintenance — rinse and store at room temperature (15–25°C); minimal upkeep required

Ideal Applications

Drinking water quality verification: tap water, filtered water, bottled water
Reverse osmosis (RO) systems: pre- and post-filter TDS monitoring
Water softeners and filtration systems: performance verification
Hydroponics and aquaponics: nutrient solution TDS checks
Aquariums: water purity and mineral content monitoring
Environmental field sampling: general water quality screening

Eco Series Model Comparison

Model	Parameter	Best For
5021	Conductivity (EC)	General water conductivity & hydroponics
5031	TDS	Drinking water, RO systems, purity checks
5041	ORP	Pools, spas, disinfection monitoring
5051	Salinity	General salinity monitoring
5052	Saltwater Salinity	Saltwater aquariums & marine testing
5053	NaCl Salinity	Sodium chloride concentration checks

Technical Specifications

Parameter	Specification
Measured Parameter	Total Dissolved Solids (TDS)
Sensor Type	Fixed, dedicated TDS sensor
Format	Single Unit (1-EA)
Storage Conditions	15–25°C (room temperature)
Weight	6 oz (approx. 0.375 lbs)
Series	Eco Series Compact Pen Testers