Review on Hanna Instruments Marine Calcium Checker by Kelly Thompson

Works as advertised. I've compared this to the API calcium test and it's right in the range. Difficult to compare accurately as the API has a maximum resolution of 20 PPM. I like using Hanna as it shows (within the accuracy of the device) exactly how much calcium is in the tank. Since I use the Balling LIte dosing method in the aquarium, I would like to know how high the calcium level is every few days, which is very convenient for me. I can do the test in about 5 minutes and get an accurate calcium reading. I don't know why some people have problems with accuracy. I use RO/DI water (I use lab grade). I am tracking DI and silica changes and my TDS is zero. I ran the test twice in a row to see if there was much of a difference in the readings and each time it was within 5ppm. I attribute this to a slight difference in the sample/reagent added via the pipette. I think the hardest part is adding the active reagent. I have found that it is easier to add the reagent to the solution if you cut open the top and use small scissors to slit the pouch. This creates a V so that the reagent can slide into the vial. Make sure you have added all your reagents. And be consistent when adding sample and liquid reagent. For me, this is an extremely useful test device in my arsenal for monitoring my tank. I also have a Hanna phosphate and alkalinity tester. I would also recommend checking the alkalinity. Phosphates are typically low in my aquarium, so a phosphate tester is never used. The downside is that the API calcium test is cheaper per test in my opinion. The powder reagent is quite difficult to add and you have to be careful when adding it. The price of replacement reagents is not cheap either. Quick price (from memory) for Hanna: $0.76 per test (test cost not included). Can I live without a Hanna Calcium Meter? Of course, since the API test works. But I would do without it. I would give 4.5 stars. Since I can't give 1/2 star, I've rounded up. If the calcium tester used all liquid reagents I would give 5 stars.