help with test kits

[dv3]

so im using salifert test kits and have a few questions

1.) when you draw the fluid into the 1ml syringe with the plastic tip on how much fluid do you get in the syringe ...i usally get between 7.5 and 8 ...which is can create a pretty big margin of error for the alk test .....anyone know exactly what it should be?

2.) when do read the results? ... is it when the color first starts to change or after it stops changing ..i.e. sometimes you will get a purple color and if you add another drop or two it will fully change to a blue or pinkinsh

[wharyat]

1. You're still getting the full 1mL of fluid. It may be reading 7 or 8 but the rest is in the tip. The bubble of air at the plunger is from the plastic tip. The tip is filled with the fluid that displaced the air.

2. Right after the color drastically changes is when to read.

[dv3]

Originally Posted by wharyat

1. You're still getting the full 1mL of fluid. It may be reading 7 or 8 but the rest is in the tip. The bubble of air at the plunger is from the plastic tip. The tip is filled with the fluid that displaced the air.
I understand there is supposed to be air but how much air? ..my fluid level is not always the same but the volume of the tip does stay the same ...i assume the seal on the plunger is letting air in the syringe and create different amounts of vacuum which is why the levels can be different ...so i guess what i asking is what is the volume of the tip?
2. Right after the color drastically changes is when to read.
so if blue changes to purple then changes to pink after a few more drops ...which is a drastic change, purple or pink?

[wharyat]

I've never paid attention to how much air, as long as I don't use more fluid than is in the syringe (which should never happen) it doesn't matter. You're counting how much you put into the test tube.

Blue to pink is more drastic than blue to purple. It will also say what color changes to what in the kit instructions.

[dv3]

Originally Posted by wharyat

I've never paid attention to how much air, as long as I don't use more fluid than is in the syringe (which should never happen) it doesn't matter. You're counting how much you put into the test tube.
well the air is important to the extend that the more air you have the less fluid you have ...so says your plunger is on the 1ml mark but sometimes the fluid reads .075ml and .08 ml another time that can make your alk off by over 1 dkh
Blue to pink is more drastic than blue to purple. It will also say what color changes to what in the kit instructions.
ok how bout this one ...the mag test ...the instructions say read when it changes to gray or blue ...well what does gray water look like? ...to me a light bluish purple could be gray ? .....but if you add more drops i becomes a much lighter blue

maybe i'm just over analyzing this but i am just trying to make sure my results are accurate as possible

[whatevva]

Don, you are correct. This leaves a large margin for error. I've found that if I haven't tested in a while and the syringe is dry, I get a larger bubble. So what I do is draw the fluid into the syringe, empty it, then refill. You'll find that this will give you, very close to, the same bubble line each time.