5 meq O₂/kg @ 25°C

Refill with clean electrolyte solution

Watermelon

Big Blue vs

Hanna Instruments HI781-25 Marine Nitrate Reagents for Saltwater Aquariums (25 Tests) Bluelab OnePen replacement probe 5 meq O₂/kg @ 25°CHanna Instruments HI781 25 Marine Nitrate Checker Reagents (25 Tests) Keep your reef and saltwater aquarium thriving with Hanna Instruments HI781 25 replacement reagents precision formulated for use exclusively with the HI781 Marine Nitrate Low Range Colorimeter. Each packet is pre measured for fast, accurate nitrate testing with zero guesswork. Why Choose HI781 25 Reagents? Pre measured packets no mixing, no mess, consistent results every time. High