Salifert Test Kits

[twychopen]

Ok, I have been wondreing this ever since I started testing with the Salifert test kits. I hope someone else has too...

On any of the tests that use the 1,00 ml syringe (Calcium, KH/Alk etc) how do you do the last step? Do you just read the tick that the liquid is at in the syringe and match it to the chart or do you subtract where the liquid started and where the liquid ended and use that value as the number to match on the charts?

If it is the first option (Using Calcium), lets say that when I suck up the chemical into the syringe the tip of the piston (black part) is at 1,00 and the liquid is at ,75. If it moves down ,10 it is now at ,65 and my reading of Calcium is 175ppm.

If we did the same thing but the liquid filled to ,80 and went down ,10 to ,70 the reading would be 150ppm but the same amount of reagent would be used to cause the color change. Technically the calcium levels would be the same but would read differently on the tests. Can anyone explain the correct way to use it?

(note: mine always fills to ,75 unless I use it more than one time in a row! If I use it on two different tests/tanks the second time it fills to ,78 or ,80)

[Europhyllia]

If I read the instructions correctly then the small part of air is accounted for (assuming you kept the tip in the liquid the whole time and the air is just what was in the tip of the syringe to begin with) and the results should be read from the edge of the black rubber part - not the liquid.

[SaltyJim]

If I read the instructions correctly then the small part of air is accounted for (assuming you kept the tip in the liquid the whole time and the air is just what was in the tip of the syringe to begin with) and the results should be read from the edge of the black rubber part - not the liquid.

+1

The "air" space is the equivalent to the volume of air that is added when you snap the tip on. If you were to remove that tip, submerge and draw the reagent, then the liquid level would be at the 1.00mL mark.

Just to keep things the same (on my end at least), I always fill till the bottom (as I hold the syringe point down) of the plunger is at the 1.00 mark. Then, when I read the reagent level, I hold it point up, and read the number at the top of the black ring. That number corresponds to the numbers on the chart. You should not have to do any math unless you are using the low end test.

HTH.
Jim

[twychopen]

Ok, so if thats the case, what if you use it twice in a row? I just tried it again and it first was at 75 then at 78 the next time i filled it. Both times the piston was at the 1.00 mark (the bottom of it if it is held with the tip down)

[Europhyllia]

A man with one watch always knows what time it is; a man with two watches can never be sure... (chinese proverb)

I have only one tank so I only test once and put it away again. How big is the difference in results between 0.75 and 0.78?
I guess I am happy enough with an approximate correct answer as long as it's not a huge range.

[Bill S]

Where the liquid is does not matter - as long as you didn't suck air up when you filled the syringe. The plunger tells you how much was dispensed, and unless you have a way of titrating with the syringe pointing up, you always get reagent coming out. In the rare instance you need more reagent (like when dosing Mg to get rid of byropsis and it's off the charts), just add more and continue titrating.