Did I use this thing right? It didn't have very helpful instructions so I guessed at it.
Clean the prism and flippy thing with pure water
Put a drop of tank water on the prism
Close the flip top and smooth out any bubbles
Wait a ten count for temps to equalize
Take the reading
Clean the prism and flippy thing with pure water
Put a drop of tank water on the prism
Close the flip top and smooth out any bubbles
Wait a ten count for temps to equalize
Take the reading