meter will not tell you what the dissolved solid is that is getting through, so IMO
that is not a good way to determine if there is iron or not.
I have iron in my water and I just have to change out the micron filter more then others do. Does not effect the membrane IMO
. It has to go through 2-3 filters before the membranes and the carbons and prefilters remove the iron. I installed a pre pre filter to helps with this issue. I bought a iron test kit at HD to test my water..