Different Calcium Results

[PodRod]

I know there was a thread about this awhile back but I can't find it. I was out of test kits for calcium so I purchased both Salifert and API. The Salifert shows a calcium reading of 410, yet the API shows 480. Both kits are new. My old test kits (Salifert and API) had a difference of 10 so I never worried about it. With these new kits, I don't know which one is correct and the difference is much larger now. Any ideas?

[StevieT]

did you do multiple tests with each?

 

API is regarded as accurate, yet salifert is #1 in most eyes.

[Weetabix7]

Here is some info copied from one of ezcompany's posts on my Prop Tank thread:

 

Weetie, I hope you didn't purchase seachem test kits for calcium, they have been known to read very low.

Apparently for magnesium as well. Here is a recent test kit comparison done by Billy on RC

 

CALCIUM

 

Elos 400 ppm

LaMotte 400 ppm

API 400 ppm

Salifert 415 ppm

Seachem 340 ppm (we've been down this road before)

 

ALKALINITY

 

Elos 10 dkh

LaMotte 7.8 dkh don't know whats up wit that

API 10 dkh

Old Salifert (with indicator) 10.6 dkh

New Salifert (without) 11 dkh

Seachem 9.8 dkh

 

MAGNESIUM

 

Elos 1350 ppm

Salifert 1350 ppm

Seachem 1060 ppm

[PodRod]

StevieT - I did each test twice because I thought I'd made a mistake the first time around. My old test kits were the same two brands and, as recently as last week, were showing only 10 difference between the two. I threw my old test kits away since they were almost empty. I'm now at a loss with the new kits since I don't know which one is correct.

 

Weetie - thanks for the test comparisons. I now remember it was your thread I was looking for. Even with the test results you posted, the Salifert tested higher than the API. Mine is the other way around with Salifert at 410 and API at 480.

 

I'd like to believe the API is right but I've always struggled keeping my calcium levels up with TM salt so I'm thinking the Salifert is the more accurate of the two. I would buy a third kit but it would probably give me an entirely different reading and then I would go nuts...

[imisky]

the difference between the 2 kits seem to big imo, i have both the API and salifert kits and my experience with them has never been off as much as 70ppm like in your situation. i have personally switched from using saliferts over to APIs as APIs seem to test out close to the elos.

 

if you can mix up a known concentration of Ca in some RODI water then use the test kits to measure it you'll know which one is the accurate one thats what i did with my salifert and API to see which is closer to the actual PPM i set in some RODI water.

[PodRod]

the difference between the 2 kits seem to big imo, i have both the API and salifert kits and my experience with them has never been off as much as 70ppm like in your situation. i have personally switched from using saliferts over to APIs as APIs seem to test out close to the elos.

 

if you can mix up a known concentration of Ca in some RODI water then use the test kits to measure it you'll know which one is the accurate one thats what i did with my salifert and API to see which is closer to the actual PPM i set in some RODI water.

 

That's a great idea! Since I know what my TM mixes to I'll check it tomorrow and that should tell me which kit it correct. I'll post the results tomorrow - thanks!

[bilge rat]

uuhhhmmmm

 

i use seachem

 

is this the general feeling towards seachem is that they are inaccurately low?

[PodRod]

Wow - that didn't take long. I tested make-up water that I have mixed for my next water change. I first used my API test since I suspected it was the one that was wrong. I got a reading of 340, which is consistent with what I've always gotten with TM salt. I then used my Salifert test and was shocked to see a reading of 270! Once again, a difference of 70. This new Salifert test kit is WAY off and I'm in much better shape with my calcium levels than I thought.

[lakshwadeep]

I saw one on my local city's "government access" channel a show that highlights different departments and what their employees do in a normal work day. Well, the episode I saw had a person from the water department who tests different water sources, like rivers, runoff ditches, and sewer systems. I was surprised to see the tests being used were from LaMotte.

[masterbuilder]

LaMotte seems to be the preferred kit in most all labs for a quick and dirty test.

[divecj5]

Interesting find PodRod....makes me feel a lot better about using the cheaper API tests. At about 1/5 of the cost of Salifert, strange that Salifert would be off by that much. Goes to show that even the best companies can have a bad batch of products.

[The Propagator]

You really cant go to wrong with API as long as the kits your using are not out of date.

I have used them for a long large time.

I tried dry tabs when they came out. SUCKED BAWLZ.

I have tried them all I think..

Lamotte a LOT more expensive then API and only off by a small amount from my API

Seachem SUCKS BALWZ

Instant Ocean SUCKS BAWLZ

Salifert Little more expensive and the same readings as my API

Elos little more expensive an a little more accurate then API but your limited to what you can find.

Most of the time you can only find ALK and Mag.

[bdare]

You really cant go to wrong with API as long as the kits your using are not out of date.

I have used them for a long large time.

I tried dry tabs when they came out. SUCKED BAWLZ.

I have tried them all I think..

Lamotte a LOT more expensive then API and only off by a small amount from my API

Seachem SUCKS BALWZ

Instant Ocean SUCKS BAWLZ

Salifert Little more expensive and the same readings as my API

Elos little more expensive an a little more accurate then API but your limited to what you can find.

Most of the time you can only find ALK and Mag.

Yeah... What he said.

I concur.

+1.

Exacly.

Ditto.

I agree.

WORD to your mutha.