Hanna Instruments HI-4004-51 Calcium Module for Half Cell
The HI-4004-51 is a replacement sensing module for the calcium half-cell Ion Selective Electrode.
Used with the HI-4004 calcium half-cell Ion Selective Electrode (ISE), the liquid membrane sensor contains an organic polymer within the PVC matrix which is responsible for exchange of calcium ions across the membrane.
A charge imbalance develops between the sample and the internal cell in response to the calcium ion activity.
The HI-4004-51 calcium half-cell module easily fits onto the HI-4004 probe body, allowing for quick replacement.
Pre-soaking the calcium sensor in HI-4004-45 conditioning solution or a calcium standard (0.01M) without ionic strength adjuster (ISA) for a while before calibration will help to optimise the sensor response.
Refrigeration of the HI-4004-51 calcium module will help extend its life.
Frequently Asked Questions
Clear answers to help you choose the right water testing solution with confidence
Which brands of water testing kits do you supply?
Do you provide kits for both home and professional use?
Yes — whether you’re a pool or spa owner, aquarium keeper, utility company, or a university laboratory, we have the right solution for your needs.
Can I arrange servicing or calibration for my photometer?
Absolutely. We also provide servicing and calibration to keep your photometers accurate and reliable.
How quickly do you dispatch orders?
Orders placed before 2:30 pm (Monday–Friday) are dispatched the same day. We also ship on Saturdays for your convenience.
Which couriers do you use for delivery?
We deliver through UPS, DPD, and Royal Mail. You can also choose to upgrade to next-day delivery at checkout.
What is your return policy?
We accept returns within 14 days of delivery provided the items are unused, in their original packaging, and in resalable condition. Please contact our team before returning any items.
Can I place bulk or business orders?
Yes, we welcome bulk, trade, and institutional orders. For tailored pricing or large quantities, please get in touch with us directly.
How can I get help if I’m unsure which kit to buy?
You can call us at 📞 +44 (0)115888 2726 and our team will guide you in choosing the most suitable kit for your needs.