Salifert KH test question

[charlestonemt]

Let me begin by saying that I know I'm probably overthinking this and I'm sure there is an easy answer. Now with that out of the way....

I just started using this test. Instructions state to put a plastic tip onto the 1mL syringe and draw up the reagent until the plunger is at the 1mL mark. It notes that there will be some air present below the plunger, and that this is normal because it's the air that was present in the plastic tip. Then drop-by-drop add the reagent until a color change appears, look at the mark the plunger is at, and then compare it to the printed chart in the instructions to get the KH/alk reading. Now here's what confuses me: once you get to somewhere around .15mL left in the syringe, all of the reagent has been expelled from the syringe and there is nothing but air left for the remaining .15 (or so) mLs. However, there are still calculations on the chart all the way to 0.00 mL. Does anyone understand why I'm confused?

 

[charlestonemt]

Wait a minute...I think I just figured it out. Although there is nothing but air in the syringe for the last .15 mL or so, there will still be an identical amount of reagent present in the plastic tip until all the air is removed from the syringe itself, so the measurements are sitll accurate. Right? Does this make sense to anyone?

 

[funkpolice]

bingo, bango
bill

 

[BarbMazz]

Yep, you figured it out!

However, be aware that Salifert had a bad bunch of alk tests, so if your number for alk seem out of whack with the rest of your params you might want to pick up another brand of test.

I had a bad test, and so did nikkipigtails. Both our alks were testing WAY high in comparison to calcium/magnesium.

I picked up an Elos alk test and boy it's sure a lot easier to use, although pricey.

 

[mps9506]

Wait a minute...I think I just figured it out. Although there is nothing but air in the syringe for the last .15 mL or so, there will still be an identical amount of reagent present in the plastic tip until all the air is removed from the syringe itself, so the measurements are sitll accurate. Right? Does this make sense to anyone?

yep.