Cover more than one total-hardness range with the correct chemistry
Choose the mixed HI93735-0 assortment when your work genuinely spans low, medium and high total hardness. Keep range-specific reagent A matched to the selected method, with the indicator, buffer and fixing reagent specified in the instrument manual.
Manufacturer identification photo; labels do not establish current packing, stock lot or expiry.
Choose the right role, range and method
Total hardness as CaCO3: LR 0–250 mg/L; MR 200–500 mg/L; HR 400–750 mg/L.
HI97735, HI83300 and HI83399 manuals explicitly list HI93735-0. The three ranges use different A reagents; this is not one chemistry with a wider numerical display range. Total hardness measures the calcium/magnesium response on a CaCO3 equivalent basis. Alkalinity can use the same unit but measures a different property and requires different reagents.
Choose mixed-range or single-range according to actual use
If you routinely work in just one range, the separately offered HI93735-00 (LR), HI93735-01 (MR) or HI93735-02 (HR) may be the appropriate refill. This page is only for mixed HI93735-0 and does not replace those products. Choose by expected sample range and exact instrument method, not a blanket savings assumption.
Capacity clarification before relying on a pack count
The current US manufacturer listing calls HI93735-0 a 100-test product. HI97735, HI83300 and HI83399 manuals instead list 300 total tests: 100 LR + 100 MR + 100 HR. These statements conflict. The manual capacity is quoted as a method/order reference, not an unqualified promise of the current US physical pack. Confirm the supplied packing and usable capacity before ordering to a required test count.
Chemistry and equipment to check
The documented methods require HI93735IND-0 indicator, the selected HI93735A-LR, HI93735A-MR or HI93735A-HR, HI93735B-0 buffer and HI93735C-0 fixing reagent. This mixed reagent assortment is not a photometer starter kit. Have a compatible instrument, correct cuvette/cap/stopper, accurate 0.5 mL dosing equipment, refilling pipette and a clean wiping cloth. CAL Check standards are separate verification materials, not analytical reagent replacements. Bottle fill volumes, packet counts and accessory inclusion are not inferred from doses or photographs.
Protect the range-specific color measurement
On HI97735, select LR, MR or HR before preparing the sample. The method uses 0.5 mL sample, 0.5 mL indicator, 9 mL of the matching A reagent and two drops of B. Zero before adding one packet of C; gently shake for 20 seconds before reading. Use the complete instructions for your exact instrument; excessive heavy metals can interfere. No heating step is specified in these total-hardness methods.
Read all six component safety sheets
Use the current US SDS for A-LR, A-MR, A-HR, indicator, B and C, not a single generic hardness sheet. Follow supplied lot labels for handling, storage, expiry and disposal. Photo labels identify the family but do not establish current packing, fill volume or stock expiry.
Frequently Asked Questions
When is the mixed assortment useful instead of a single-range refill?
Choose HI93735-0 when your actual samples and programs require multiple total-hardness ranges. For one regular range, consider the separately offered HI93735-00 LR, HI93735-01 MR or HI93735-02 HR. The mixed assortment is a separate SKU; no automatic saving or longer useful life is guaranteed.
What are the LR, MR and HR ranges?
The HI97735, HI83300 and HI83399 methods specify LR 0–250 mg/L, MR 200–500 mg/L and HR 400–750 mg/L, all as CaCO3. Match the instrument program and the corresponding A reagent. Overlapping numerical intervals do not make A-LR, A-MR and A-HR interchangeable.
Is total hardness the same as alkalinity because both use CaCO3 units?
No. This method responds to calcium and magnesium for total hardness. Alkalinity concerns acid-neutralizing capacity. A common CaCO3 equivalent unit does not make the properties or reagents interchangeable; this is not an alkalinity refill.
Does the current pack guarantee 300 tests?
Not yet established for the current US offer. The US listing says 100 tests, while HI97735, HI83300 and HI83399 manuals explicitly list 100 LR + 100 MR + 100 HR, or 300 total. We retain that manual-listed capacity with this qualification; confirm physical packing before relying on a count. It does not mean 300 tests of any one range.
Which component identities belong to this workflow?
The manuals specify HI93735IND-0 indicator; one of HI93735A-LR, HI93735A-MR or HI93735A-HR; HI93735B-0 buffer; and HI93735C-0 fixing reagent. All six component SDS are linked. Per-test doses and the factory photo do not establish supplied bottle fill volumes or packet counts.
Which instruments have direct manual support?
HI97735, HI83300 and HI83399 each explicitly list mixed HI93735-0 and their total-hardness LR/MR/HR procedures. Use the exact-model manual and matching cuvette system. A photometer measuring another hardness or alkalinity method is not automatically compatible.
What else is required, and is a heater needed?
Have the compatible photometer, correct cuvette/cap/stopper, accurate small-volume dosing equipment, refilling pipette and lint-free wipe. These accessories and CAL Check standards are not promised in the reagent assortment. No heater is prescribed in the cited total-hardness methods.
Which steps and interferences matter most?
On HI97735, prepare with the correct A reagent, indicator and B, then zero before adding C. Shake gently for the specified 20 seconds and keep the cuvette exterior clean and orientation consistent. Excessive heavy metals may interfere. Follow the full exact-model procedure and all component SDS rather than a generic water-test routine.
