Calcium Colorimeter HI758 Hanna Checker - Marine Water

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Calcium Colorimeter HI758 Hanna Checker - Marine Water

66% Recommend this to a friend (76 of 116)

SKU: 206202
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Quick Overview

Three simple steps to results. The Hanna Calcium Checker bridges the gap between simple chemical test kits and professional instrumentation. Accurate, affordable and easy to use. First, zero the instrument with your water sample. Next, add the reagent. Last, place the vial into the Hanna Calcium Checker, press the button and read the results. Done.

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Product Questions

Are the reagent packets really that hard to open and get into the vials?

It seems that the biggest/only gripe about this unit in the reviews is that it uses a powder reagent and not a liquid.

Is it really that hard to open the packet and get all of the powder in the vial?
Question by: G on Apr 20, 2016 11:16:00 AM
Great question!
We do not have issue with the packets, As long as the packet is shaken to the the power into one corner, The flap is then cut and the packet folded to allow the power to fall down the crease in the packet we have not had issues ourselves.
Answer by: Connor (Admin) on Apr 26, 2016 1:37:00 PM
does the hanna checker come with the reagents, or do I need to order regents separate?
Question by: jeremy on Nov 26, 2013 8:23:00 AM
Hi Jeremy,
The Hanna Calcium Checker comes with enough reagent to do about 25 tests.
Answer by: Bulk Reef Supply on Nov 26, 2013 8:23:00 AM
I would like to buy a Hanna checker for nitrate please but can not see one on
Your web site
Question by: Stuart ray on Apr 10, 2014 10:50:00 AM
Hi Stuart,
They do not make a Nitrate checker. If/when they do though we will bring it in.
Answer by: Bulk Reef Supply on Apr 10, 2014 10:50:00 AM

Full Details

Easier to use and more accurate than chemical test kits


The HI 758 Calcium Checker®HC is extremely simple to use.


Dedicated to a single parameter

Designed to work with HANNA's liquid reagents. Uses 10 mL glass cuvettes.

Small Size, Big Convenience

Weighing a mere 65 g (2.3 oz.), the Checker®HC easily fits into the palm of your hand or pocket.Use for quick and accurate on the spot analysis. Single button operation: Zero and Measure Operated by a single AAA battery.


  • Range: 200 to 600 ppm
  • Resolution: 1 ppm (mg/L)
  • Precision: ±6% of reading
  • Light Source: LED @ 610 nm
  • Light Detector: Silicon photocell
  • Environment: 0 to 50°C (32 to 122°F); RH max 95% non-condensing
  • Battery Type: (1) 1.5V AAA
  • Auto-off: After 10 minutes of non-use and after read
  • Dimensions: 81.5 x 61 x 37.5 mm (3.2 x 2.4 x 1.5")
  • Weight: 64 g (2.25 oz.)
  • Method: Adaptation of the zincon method



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  • Not worth buying By Joshua on 10/13/2016

    I have a couple other Hannah checkers which work flawlessly the precise they're accurate and you can check them against other test kits with out any difference you can repeat the tests and get for the most part the same exact numbers however ....
    I'm a medical professional I know how to draw up exact amounts of fluids and titrate I have followed the Hannah directions for the calcium meter exactly to a T and I cannot get the meter to reproduce The same test values ever . I took a sample of water and a clean sterile syringe filled up Both cravats and ran the test twice each one when compared to the Red Sea pro said the calcium was somewhere between 50 and 75 ppm higher than what the Red Sea showed . If it was five or 10 ppm that's not a big deal I could live with that but 50 or 75 ppm could theoretically mean the death of prized corals or the starvation of prize corals that I have worked very hard to keep alive.
    That being said if you're looking at other Hannah checkers bite the bullet because they're worth it but I would steer clear of the calcium and a checker and use a traditional titration such as the Red Sea, Nyosor even an API kit .
  • don't trust this checker By jason on 9/29/2016

    i do not dose my tank at all this checker one day give me 380 reading the next day give me 530 the third day 460 i m going crazy with this thing do not buy it
  • Works as advertised By Josh on 9/17/2016

    I haven’t run into any of the issues the others have. I can perform this test in a couple of min. and it’s accurate. I’ve compared it to other tests (even Triton Labs) and it has been within a few points. I’ve also have not seen inconsistencies between tests.
    I prefer this much more than trying to read colors
  • Not accurate By Mark on 8/29/2016

    This test takes almost as long as using titration via Red Sea's test and seems to read higher than Red Sea (60-80ppm higher). The sample size of tank water 0.1ml is way to small. if your off by a drop, your readings are skewed. I love their Alkalinity checker though!!!
  • Different results, same water, minutes apart By virginia on 8/27/2016

    Results extremely high, retested for accuracy, got different high readings everytime. Not what I was expecting from a digital test. Was expecting to trust digital reading, not if the same water has different results from testing and retesting for accuracy and extremely high numbers in the 500
  • Very inconsistent readings render this checker useless. By John on 8/17/2016

    I use quality ro/di water (with 0 tds) and am very meticulous in the testing process. I have been wondering why I was having difficulty stabilizing the calcium levels in my tank. Today, I decided to repeat the testing to insure consistency. Three identical tests within 15 minutes yielded calcium levels of 334, 496 and 429. Problem solved - These wildly varying results are completely unaccepable and render the checker useless. Called Hanna and they want me to use their DI water for testing and are sending a "more accurate" syringe....
  • What junk By Mikey on 7/19/2016

    Can not get two results within 75-100 ppm. Contacted Hanna, we will see if they will back their product. It must be defective? I don't believe I'm that stupid or am I????
  • While I would recommend this checker it is much more cumbersome than the alkalinity checker By Chris on 6/23/2016

    Since this checker requires dilution and two reagents its much more difficult than the ultra simple alkalinity checker. One of the biggest issues is the powder reagent. you have to cut 3/4 of the packet and bend it in a certain way to make sure the entire contents come out into the test vial without spilling. there have been a number of times where I spilled some and rather than risking a bad reading I just started over.
  • Bottom line, I want speed and accuracy. This fails on both By Ryan on 6/14/2016

    Fact is there are much easier Calcium test on the market. I was hoping for the same ease of use as the Alk and this test let me down. Too many variables to screw up if not exactly precise. The packets of reagent are annoying. Bottom line, it's a slow test, easy to get a bad reading and for $50 fell terrible short. I can use the API test and get my Calcium reading in 2 min for half the price. I will not use this test kit again.
  • Hanna By Robert on 6/1/2016

    I have read the reviews here and I think a lot of the bad reviews is operator error, if you take the time to make sure the testing vile is cleaned out every time and rinsed with RODI water, and testing is done with good RODI water you will find this kit works well!
  • Results within range of accuracy By Stratos on 5/2/2016

    Although the Kh tester is much easier and straight forward this guy is a little trickier. The trickiest part of all is the reagent pouches that have to be emptied and I suspect that's the biggest factor of error. A lot of people complain about it's readings but the kit does say " ±6% of reading" which means that for a reading of 420 ppm the error is ±25 ppm. I find that acceptable since titration tests are hard to read especially for my eyes. All in all, the only thing I would suggest changing is the dispensing of the solid reagent.
  • Questionable accuracy By Larry on 4/25/2016

    While I LOVE the Hanna Alkalinity tester - I have issues with the Calcium tester.

    I ALWAYS test 2-3 times and will usually get 2-3 different results - sometimes VERY different.
    Which means I am going through the reagent very fast.

    It IS easier than the Red Sea kit but, If you don't get consistent results then you can't trust it. And if you can't trust it then why even bother.