Calcium Colorimeter HI758 Hanna Checker - Marine Water

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Calcium Colorimeter HI758 Hanna Checker - Marine Water

67% Recommend this to a friend (76 of 114)

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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  • 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.
  • Incredibly Useless By Ray on 4/16/2016

    I hate titration, but this test wins. First it was wildly inaccurate, probably because you need a full lab with bright lights, deionized water, and a way to empty the packet without spilling or breathing, and get it in a hole the size of a pencil. Return to sender this thing sucks. The test showed 200, red sea daily tests show 390. If they could find a way to dispense the packet, the show scissors cutting around it entirely like you would empty it into a stainless mixing tray with a pour spout or something. Then the syringe is barely readable except under metal halides. Ya, do not waste your money on this one. I love their KH though.
  • Not accurate or consistent. By Rick on 4/13/2016

    I had high hopes that this kit would make testing easier. I even bought another Hanna checker before this one even arrived. First, I've been reef keeping for nearly 20 years.

    I checked against two other test kits, both Salifert. Both kits said 390 +-6 over 2 tests each. Hanna said 361, then 470. That makes this test kit useless.

    Hanna, if you can fix the accuracy and consistency, I have a few suggestions. First, the packets are ok, but a scoop works just fine for me on the Salifert kits. For current users: I figured out quickly that opening the packet with scissors across one side then open it wide to form a nice sharp point makes is easy to get into the vial.

    I don't like the dropper to get the DI water into the vial. I remember high school/college chemistry. So, I knew to put the line at the half bubble of the water. A 10ml syringe would make that step easy. And possibly more accurate?

    Lastly, I'm only 44 so my eyes are still pretty good, but the instructions are in 2pt font. The box is big enough that I think a bigger font would easily fit in the box... and be kinder to the user.