
What Makes the Hanna pH Probe Survive Feed Water
Double junction, with an Ag/AgCl reference behind a PTFE junction and a polymer electrolyte that is sealed rather than refillable. The body is PEI plastic, the tip is a 7.5 mm sphere, and it runs 0 to 80 °C. The lead is 2 m of coaxial cable ending in a BNC plug.
Where This Replacement pH Electrode Will and Will Not Fit
The second junction is the part that matters in a nutrient tank. It keeps the reference chemistry one step away from the sample. Phosphate and nitrate reach it far more slowly than through a single junction. That is the difference between an electrode that clogs early in a heavy feed and one that keeps reading. It goes into any meter with a female BNC socket, so a GroChek monitor is the common home but not the only one. Store the tip wet in storage solution between runs. Never dry, and never in deionised water, which pulls the fill straight out through the junction. Every glass electrode still ages, and this construction slows the clogging without stopping the clock.
Key Features
- Double junction: Keeps the reference chemistry a step away from phosphate and nitrate in feed water.
- PTFE junction: Resists the salt bridging that closes a ceramic junction in a nutrient tank.
- Polymer electrolyte: Sealed, so there is no fill to top up and nothing to spill.
- PEI plastic body: Tougher than glass in a room where a probe gets knocked against a tank wall.
- 2 m coaxial lead, BNC plug: Long enough to sit the meter outside the reservoir and clip the lead clear.
- Fits more than GroChek: Any meter with a female BNC input takes it, not just the monitor it shipped with.
- 0 to 80 degrees C: Covers reservoir, runoff and warm source water without special handling.
- Still a consumable: Slower to clog than a single junction, but every glass electrode eventually ages out.
Technical Specifications
| Specification | Value |
|---|---|
| Brand | Hanna Instruments |
| Part Number | HI1286, GrowersHouse 716806 |
| Type | Replacement pH electrode |
| Reference | Double junction, Ag/AgCl wire |
| Junction | PTFE |
| Electrolyte | Polymer, sealed, not refillable |
| Body Material | PEI plastic, also sold as Ultem |
| Tip Shape | Spherical, 7.5 mm diameter |
| Operating Temperature | 0 to 80 °C, 32 to 176 °F |
| Cable | Coaxial, 2 m, 6.6 ft |
| Connection | BNC |
| Fits | GroChek monitors including HI981401N, HI981402 and HI981404N |
| Also Fits | Any pH meter with a female BNC input |
| Best For | Nutrient solutions high in phosphate and nitrate |
| Storage | Tip kept wet in storage solution, never dry or in deionised water |
| pH Range | Not published by Hanna for this electrode |