Hanna calcium checker inconsistency

[tundraguy1106]

Hey,

So I’ve been chasing 450 ppm calcium for the past few month. Been hovering around the 380 mark but just thought it was due to adding new corals all the time. My alkalinity is 9.0 also on a Hanna tester. On monday my calcium tested at 389. I added an adjustment dose of 25 ml (145 gallon system) of bionic calcium and then bumped up my dosing pump 4ml per day.

so today I tested my calcium again and it shows 381? I figured that’s not possible with the adjustment dose and bumping my daily calcium 4ml. So I decided to retest. I had to open a new reagent since the prior test was my last one. Be advised, Both the old and new ones are not expired (2/2022). So I retest and immediately notice the difference in the results color. My final color went from, purple, which it’s always been, to blue. I then check the number and it’s now showing 484!!! Over 100 point difference from the prior test. Same sample water being tested. So I decided to retest AGAIN. This time my result was 451! And again it was blue in the end and not purple. All tests were administered properly according to instructions l. Any ideas on the inconsistencies and is anyone else having these issues??
Thanks

I’ve attached the RO water I’m using and what the final result colors were.

 

[vet4him]

I've heard you need to use their "special" RODI water for it to be accurate. I have had the same inconsistencies between it and my Salifert kit. Probably gonna chuck it and stick with Salifert.

 

[Randy Holmes-Farley]

I will just add that the Hanna calcium checker is the one that causes the most problems for folks.

One reason may be that it is freakishly oversensitive to calcium in the blank. IMO, it is a bad design to make it that way.

I wouldn't expect type II DI water to have enough to be a problem, but it might be picking it up along the way to the test, or it may be something else entirely.

 

[tundraguy1106]

I will just add that the Hanna calcium checker is the one that causes the most problems for folks.

One reason may be that it is freakishly oversensitive to calcium in the blank. IMO, it is a bad design to make it that way.

I wouldn't expect type II DI water to have enough to be a problem, but it might be picking it up along the way to the test, or it may be something else entirely.

I bought special RO water because I thought my zero TDS home RODI water was the problem initially! Unreal, you buy these things hoping they’re accurate and this is what you get... smh are the saliferts reliable? Amazon reviews say yes but ya never know

 

[MarshallB]

It's extremely sensitive, but I've had consistent results with it.

The key is in the first step. Make SURE you have the EXACT amount of rodi water that you had in it the last time you checked. The way it dilutes the tank water even 1 drop in either direction can alter the results.

I use a 10 ML syringe to measure out the exact amount of water each time rather than trying to eyeball it, which for how sensitive this test is, shouldn't even be an option. They should have provided a syringe to accurate measure out the RODI water since they have syringes with exact measurements for the other required solutions in the test.

Second, in step 2 make sure you insert the vial facing the same way as you did in step 1. I make sure the side of the vial with the visible number is facing me. I also use the same vial for every test.

For me, coming from the Redsea test I prefer this one any day over it. My results are usually +/- 010. Which for me is enough.

 

[PatW]

I have heard that the Hanna Calcium checker is .... challenging. I have had good luck with Red Sea Pro and I bet Salifert it decent also. With Alkalinity, I want to be as close as possible. But with calcium ball park is good enough. Bulk Reef Supply has a video comparing calcium tests and I don’t take them as the last word but the video shows how the tests are done and the strong and weak points.

 

[tundraguy1106]

What about the Red Sea pro? I used to use those years ago. Thought Hanna was the answer!

It's extremely sensitive, but I've had consistent results with it.

The key is in the first step. Make SURE you have the EXACT amount of rodi water that you had in it the last time you checked. The way it dilutes the tank water even 1 drop in either direction can alter the results.

I use a 10 ML syringe to measure out the exact amount of water each time rather than trying to eyeball it, which for how sensitive this test is, shouldn't even be an option. They should have provided a syringe to accurate measure out the RODI water since they have syringes with exact measurements for the other required solutions in the test.

Second, in step 2 make sure you insert the vial facing the same way as you did in step 1. I make sure the side of the vial with the visible number is facing me. I also use the same vial for every test.

For me, coming from the Redsea test I prefer this one any day over it. My results are usually +/- 010. Which for me is enough.

It's extremely sensitive, but I've had consistent results with it.

The key is in the first step. Make SURE you have the EXACT amount of rodi water that you had in it the last time you checked. The way it dilutes the tank water even 1 drop in either direction can alter the results.

I use a 10 ML syringe to measure out the exact amount of water each time rather than trying to eyeball it, which for how sensitive this test is, shouldn't even be an option. They should have provided a syringe to accurate measure out the RODI water since they have syringes with exact measurements for the other required solutions in the test.

Second, in step 2 make sure you insert the vial facing the same way as you did in step 1. I make sure the side of the vial with the visible number is facing me. I also use the same vial for every test.

For me, coming from the Redsea test I prefer this one any day over it. My results are usually +/- 010. Which for me is enough.

With Hanna I measure to the line. I add exactly the correct amount of part A and then fill the cuvette up to the line with RO water. The line should be accurate since I measure part A with a syringe.

 

[tundraguy1106]

It's extremely sensitive, but I've had consistent results with it.

The key is in the first step. Make SURE you have the EXACT amount of rodi water that you had in it the last time you checked. The way it dilutes the tank water even 1 drop in either direction can alter the results.

I use a 10 ML syringe to measure out the exact amount of water each time rather than trying to eyeball it, which for how sensitive this test is, shouldn't even be an option. They should have provided a syringe to accurate measure out the RODI water since they have syringes with exact measurements for the other required solutions in the test.

Second, in step 2 make sure you insert the vial facing the same way as you did in step 1. I make sure the side of the vial with the visible number is facing me. I also use the same vial for every test.

For me, coming from the Redsea test I prefer this one any day over it. My results are usually +/- 010. Which for me is enough.

Second step as with all Hanna Tests I face cuvette number side towards me. All my other hannas are fine. This one is always off.

 

[homer1475]

Hanna calcium is umm........I cant use those words here!

Salifert is very repeatable, and cheap.

 

[MarshallB]

What about the Red Sea pro? I used to use those years ago. Thought Hanna was the answer!


With Hanna I measure to the line. I add exactly the correct amount of part A and then fill the cuvette up to the line with RO water. The line should be accurate since I measure part A with a syringe.

I wasn't trying to say you don't measure correctly. I was simply saying 'fill to this line' isn't ideal for a test that relies on such a small amount of test water that gets massively diluted. Measuring to the line can be slightly off and not really be noticeable to the eye. For this test all measurements have to be exact. It's just strange to me that the other parts of the test are exact except the RODI portion.

Either way, for the price of the test kit I think it could certainly be better.

As for the red sea pro my results were coming in +/- 30. All the steps were just kind of a hassle too, and the dry regent started clumping up and wouldn't fully disolve after only 3 tests. I'm not sure why either. It never got wet.

 

[schuby]

I get consistent, accurate (compared to my RedSea test) with the Hanna Calcium checker if I use store-bought distilled water and not RO/DI water. When I used RO/DI, my readings were too high.

What is your Magnesium level? I believe that proper levels of Magnesium, 1250-1350 ppm, allow us to keep higher Calcium levels in our tanks.

 

[Dr. Jim]

I find the Red Sea kit gives me results closest to ICP tests when compared to Salifert.
Also, R.S. calls for 5cc of sample water while Salifert uses only 2 cc. The smaller the volume of water, the greater the chance for error due to inaccurate measuring.

 

[tundraguy1106]

I find the Red Sea kit gives me results closest to ICP tests when compared to Salifert.
Also, R.S. calls for 5cc of sample water while Salifert uses only 2 cc. The smaller the volume of water, the greater the chance for error due to inaccurate measuring.

Probably why the Hanna is so inaccurate. It uses a tiny squirt of tank water... smh

 

[rmurken]

This may be a hijack, and if so, my bad. But query whether precision is all that important in a Ca test? I would focus more on making sure your Ca/Alk maintenance keeps your Alk steady. Ca should kind of take care of itself. As long as the test doesn’t give you alarmingly high or low results...meh, life goes on.