Which Calcium test kit do you trust?

[CasperOe]

Hi Reefers,

Today, i set out to try all my calcium test kits and compare the results. Here’s what i got:

Red Sea: 350 ppm
Hanna: 416 ppm
NYOS: 250 ppm

Now- which one do i trust?

I reckon the correct answer should be ‘none of them’- so which ones do you use; and why?

Cheers!

 

[Mark Novack]

I see your problem. That is too much error gradient to even start to choose. Perhaps try some newly mixed water with a known plus or minus of the major elements and see if one is believable to 10%.

 

[CasperOe]

I see your problem. That is too much error gradient to even start to choose. Perhaps try some newly mixed water with a known plus or minus of the major elements and see if one is believable to 10%.

Aye, I might give that a go!

Up until now I have been ’trusting‘ ie. using my Red Sea test kit for calcium with he Hanna just lying around in a drawer somewhere.. Now i do not know what to trust

Our new tank will be set up with Triton so when i send in my first ICP in a month or so, i reckon i will have a clearer picture of what to believe..

 

[PatW]

I use Red Sea blue bucket mix. I have found that Red Sea salt has decent consistency at least so far. The nice thing about it is it gives the calcium, alk and mg levels that it should have for various levels of salinity. So I have used that as a pseudo standard for my calcium test. I use Red Sea PRO and it has worked for me And has come pretty close to the Red Sea mix published levels. I am not saying that you do this but if you really want, you can probably come up with a decent standard that is at least ball park and good enough for a hobbiest.

Tests give relative results. They tell you if things are changing and about how much. But unless calibrated against a standard, you really do not know the exact level. To make things worse, most tests have an end point you are supposed to reach by color change and that is interpretation. Two people using the same test might and probably will get somewhat different results based on their interpretation of the end point. I seem to be pretty consistent day to day on my interpretation.

The thing about calcium is that anything above say 280 - 350 is probably fine so you have a pretty wide latitude. I measure calcium once per week and adjust. The tank does not seem to mind a change in calcium. The corals can be pretty sensitive to a change in ALK but that is another thing.

 

[CasperOe]

I use Red Sea blue bucket mix. I have found that Red Sea salt has decent consistency at least so far. The nice thing about it is it gives the calcium, alk and mg levels that it should have for various levels of salinity. So I have used that as a pseudo standard for my calcium test. I use Red Sea PRO and it has worked for me And has come pretty close to the Red Sea mix published levels. I am not saying that you do this but if you really want, you can probably come up with a decent standard that is at least ball park and good enough for a hobbiest.

Tests give relative results. They tell you if things are changing and about how much. But unless calibrated against a standard, you really do not know the exact level. To make things worse, most tests have an end point you are supposed to reach by color change and that is interpretation. Two people using the same test might and probably will get somewhat different results based on their interpretation of the end point. I seem to be pretty consistent day to day on my interpretation.

The thing about calcium is that anything above say 280 - 350 is probably fine so you have a pretty wide latitude. I measure calcium once per week and adjust. The tank does not seem to mind a change in calcium. The corals can be pretty sensitive to a change in ALK but that is another thing.

Thanks, very helpful indeed!

I do check my calcium once per week, and the tank is doing just fine! It was only this time I thought; "hmm, maybe I should compare the test kits that I have" and BOOM! Confusion

I will continue using my Red Sea test kit and maintain a stable level of calcium. All my corals are doing great; none of them know that they are about to move soon though

 

[paul01609]

I can honestly say api calcium, I use it in my mastertronic and have tested it against Ati absolute ocean.
think mastertronic was 410 and Ati reference was 421

 

[CasperOe]

I can honestly say api calcium, I use it in my mastertronic and have tested it against Ati absolute ocean.
think mastertronic was 410 and Ati reference was 421

That's very close, might pick myself up one of those kits next time I head into my LFS Thanks..

 

[nereefpat]

Hi Reefers,

Today, i set out to try all my calcium test kits and compare the results. Here’s what i got:

Red Sea: 350 ppm

Sort of reasonable

Hanna: 416 ppm

Reasonable, but a LOT of folks report trouble using that specific Hanna checker.

NYOS: 250 ppm

That can't be right, unless you're sample is about 33% low on salinity

I just use API, because it's cheap, easy to use, and accurate enough (+/- 20ppm).

 

[CasperOe]

Sort of reasonable

Reasonable, but a LOT of folks report trouble using that specific Hanna checker.

That can't be right, unless you're sample is about 33% low on salinity

I just use API, because it's cheap, easy to use, and accurate enough (+/- 20ppm).

50 ml syringe, same sample was used across all three tests.

I stopped using the Hanna a while back because of the difficulty achieving consistent results.

Generally, I have been trusting the Red Sea.

I will be bringing in a sample to my LFS this week, they have a spintouch tester on hand

 

[KonradTO]

I only tried red sea so far. Lately I tested, dosed to the desired amount and tested again, and it was right on spot. You could use a calibration solution to see which one is most reliable