These guides keep the needle straight down. So my only assumption is that without the guide it’s not able to pull a full amount of reagent and a little air gets mixed in causing skewed results.It also fixed the Mg issue? Any ideas how? I can see levels rising if the trident is sucking air so it thinks it’s adding more reagent then it really is, but it’s the opposite for magnesium. Not saying it doesn’t work, but I don’t follow how it would help Mg.