Alk Test per 3 kits

[andy67]

Hello all


Chasing the Alk reading. i decided to try 3 different kits. Red Sea, Salifert, Hanna.

All were different. Test are conducted on 3 tanks

Red Sea Salifert Hanna
little 9.0 7.7 8.6

Big 8.5 7.0 8.2

Frag 7.0 8.6 6.7

What the hell. which one is correct ?

Andy

[Ifeelsick]

Look's like the redsea and hanna look closer. I actually own the salifert alk test kit which is worrying. Might buy the redsea since it's cheaper than Hanna and very close.

[disc1]

The fact that it is close to the Hanna actually makes me doubt it. I don't have a lot of respect for the hanna alk or calcium checkers. They've consistently been more problem than good.

The real answer is that nobody can tell from here. What you need to do is measure a solution with a known alkalinity level and check to see which kit gets the right answer on it. The salifert kits used to come with a check standard.

It's odd that salifert read lower than red sea on two tests but higher on the third. My money would be on operator error at that point. If there were really an issue between the two tests then the difference would at least be consistent. Maybe you were doing something wrong when you ran the tests. The volume of your sample is super critical in these tests. Make sure there's no water in the vial when you measure into it. Lots of people rinse their vials with tank water before they run the test and that is wrong, it will give you high results.

[andy67]

Here is the test with fresh salt water made this morning. Red sea coral pro

Red Sea Salifert Hanna

12.3 3.8 10.9

[vhuang168]

Originally Posted by andy67

Here is the test with fresh salt water made this morning. Red sea coral pro

Red Sea Salifert Hanna

12.3 3.8 10.9

What is the salinity?

rscp mixed to 1.025 should be mid 12s.

Salifert is 3.8dkh?

+1 on the standard test. Fauna Marin makes a calibration solution with known concentrations to check your tests with.

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[Becks]

How are you testing with the salifert because mine is pretty spot on

[Grayhead]

I have noticed a disparity between the makers of red Sea and hanna. Not just with alk but with phosphates as well. It's a shame we can't have one of these companies to provide stable products. It's hard to trust readings when they vary so much between companies. Especially when one is trying to dial in on their dosing regime

[2una]

I use Hanna + Salifert Alk & find the Hanna is ALWAYS lower than Salifert by around 0.75 area. I don't know which one is correct but use the Salifert value

[vhuang168]

Tests that we purchase are not absolutes. There are many variables that will affect the results.

Salifert tests have you scoop powder, how do you make sure the amounts are the same each time? Do you use a level scoop or a heaping scoop? Do you shake the container 1st to loosen up the granules before you scoop so you may have a looser density compared to a container that's had time to settle n compact.

Red Sea powder reagents come in a packet. How do you make sure you get ALL of it in? There always seems to be some stuck in the corner no matter how hard you try to get them out.

Get a standard solution and calibrate your test and testing methods against it. Do it for every new packet of reagent you get. That way you will know if it is off and if so by how much. Then just make sure you get that offset every time and you get consistent results.

http://www.bulkreefsupply.com/fauna-...-solution.html


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[zsuman101]

i use tropic marin alk test kit ,its the best one i have used

[Ron Reefman]

Originally Posted by disc1

It's odd that salifert read lower than red sea on two tests but higher on the third. My money would be on operator error at that point. If there were really an issue between the two tests then the difference would at least be consistent. Maybe you were doing something wrong when you ran the tests. The volume of your sample is super critical in these tests. Make sure there's no water in the vial when you measure into it. Lots of people rinse their vials with tank water before they run the test and that is wrong, it will give you high results.

Given the difference in the numbers and that the Salifert is lower in one and higher in the next, I agree with David, operator error.

I test Ca & alk with API kits. And once every 3 or 4 months I back up the API with a Salifert test (or on the rare occasion that I get a wild reading) and the Salifert and API are always very close.

[pisanoal]

Originally Posted by vhuang168

Tests that we purchase are not absolutes. There are many variables that will affect the results.

Salifert tests have you scoop powder, how do you make sure the amounts are the same each time? Do you use a level scoop or a heaping scoop? Do you shake the container 1st to loosen up the granules before you scoop so you may have a looser density compared to a container that's had time to settle n compact.

Red Sea powder reagents come in a packet. How do you make sure you get ALL of it in? There always seems to be some stuck in the corner no matter how hard you try to get them out.

Get a standard solution and calibrate your test and testing methods against it. Do it for every new packet of reagent you get. That way you will know if it is off and if so by how much. Then just make sure you get that offset every time and you get consistent results.

http://www.bulkreefsupply.com/fauna-...-solution.html


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Usually the scoopable reagents are designed to be in stoichiometric excess, and do not change results if you get a little more or a little less. You see the same thing in professional lab tests for certain things. And in this particular case, the salifert and Hannah do not use such reagents (you are probably already aware, so sorry if you do). Never used the red sea so cant comment.

Regardless, I agree with the cal solution. Salifert usually comes with standard to test. I was having a major discrepancy between salifert and Hannah, so I did some digging and retesting. Hannah came back within 5ppm of itself across 4 different tests and 2 bottles of reagent (one older/suspect, one new just opened prior to testing), but it was about 1.5 dkh higher then salifert. I used the standard that came with salifert and got within .1 dkh, so naturally I trust it more than my Hannah.

[pisanoal]

Originally Posted by andy67

Here is the test with fresh salt water made this morning. Red sea coral pro

Red Sea Salifert Hanna

12.3 3.8 10.9

That reading from salifert sounds way too low to have been done properly. The other 2 seem "within reason" for our test kits.

[andy67]

Well I found the ISSUE. guess i should read the directions before i post. I was reading the syringe from the plunger down like the red sea. bone head move on my part

[Ron Reefman]

Originally Posted by andy67

Well I found the ISSUE. guess i should read the directions before i post. I was reading the syringe from the plunger down like the red sea. bone head move on my part

Now you are getting the hang of it. Take your time and don't sweat the small stuff.

[oneofmany]

Originally Posted by andy67

Hello all


Chasing the Alk reading. i decided to try 3 different kits. Red Sea, Salifert, Hanna.

All were different. Test are conducted on 3 tanks

Red Sea Salifert Hanna
little 9.0 7.7 8.6

Big 8.5 7.0 8.2

Frag 7.0 8.6 6.7

What the hell. which one is correct ?

Andy

Just out of curiosity, how did everything look before you ran these tests? If all was well then these results really don't mean a thing IMO. A test kit gathering dust is a good thing.