Dosing/ testing head hurts 🙃

[fishkeeprian]

Hello,

I'm currently dosing ATI ESsentials 3 part.

I use the Hanna DKH for alk, Calcium Salifert and Magnesium Salifert.

I think the Hanna is great and I am having no issues with the readings.

With the Calcium and Magnesium tests, I'm getting various readings every time I do my tests.

I contacted ati and the recommend their analytic reference solution. The solution is set to specific parameters, so it allows you to determine how accurate your test kits are.

Here is the solution parameters



First I tested the Alk and the Hanna checker tested 7.5, so perfect

I test Calc and mag three times in a row and again I got three different readings. These are not little differences either.

I really don't know what to believe, and I'm bombarding myself with numbers, what should I do? What do I believe?

Just want to keep it basic.

Thanks

 

[bertoni]

How far apart were the calcium and magnesium readings?

 

[Vinny Kreyling]

Fauna Marin also makes a standard used to test various parameters sold in a small bottle.

 

[gprdypoo04]

Fauna Marin also makes a standard used to test various parameters sold in a small bottle.

You've got to be standing.

 

[Habib]

Do you rinse the test vials with water just before testing? If you do that then that would explain the variation. I can explain why but need to know first if you do that.

 

[fishkeeprian]

Do you rinse the test vials with water just before testing? If you do that then that would explain the variation. I can explain why but need to know first if you do that.

Hello,

I rinse the virals after testing with RO and air dry. Then before test I rinse with tank water.

 

[Habib]

Hello,

...... Then before test I rinse with tank water.

This is causing the variation in reading.

There is no need to rinse before testing. After testing rinsing with tap water and/or RO water followed by drying is just fine.

Never rinse with tank water.


Because of the rinsing with tank water before testing the amount of sample will show variation because the total amount is the amount to be used (2 or 4 ml depending on the test) PLUS the drops of tankwater already in the test vial because of the rinsing.

The exact amount of sample is important and the tests have been calibrated using the required amount of sample.

The pre rinse with tank water caused this amount of sample to fluctuate, hence the variation you are seeing.



A few years ago we had the same question and after going through each step with that hobbyist and not able to figure it out we almost gave up until we thought of this possibility because some manufacturers actually tell to pre rinse with tank water. Well finally that problem was solved.


Only telling this to show that it is not always easy to figure out the cause.


FWIW, a pre rinse with tank water is OK only when the amount of sample has to be filled to a certain line. Not when added with a syringe (which is a far more accurate way)

 

[Vinny Kreyling]

As a follow up on this question:
There is always a slight amount of liquid left in the syringe after dispensing into the vial.
Is this a concern or something we should not worry about?

 

[Vinny Kreyling]

There is always a slight amount of water left in the syringe after dispensing into the vial.
Is this any concern or not?

 

[bertoni]

That should be fine.