I'm having problems getting accurate readings. Here is what I mean. I seem to be off by plus or minus 0.5 or so on a given reading. I did two tests this morning within 5 minutes with no equipment running and one was a FC reading of 4.5 and the other 5.0. As best I can tell, I did everything the same way. I notice that the meniscus on my "chlorine only" cylinder is a bit stronger than the other one for what it's worth, but I try and be careful.
Is this normal for this test? Is there something I could do to make it more repeatable?