I'm looking at getting a UV meter to check bulb output, longevity, etc. I have seen Solartech, seemingly the big company to make these for our use, with two different models: Solarmeter 6.2 UVB meter $160-$230 AND Solarmeter 6.5 UVI meter $190-$280 I'm wondering if anyone has tried these? Are they easy to use? I am thinking the 6.5 would be better, but I've seen on other sites that people have said that a ratio of UVB/UVI is needed to know anything about the bulb - does this mean I would then need both? I don't really want to spend that much, but I would like to know the differences in output at varying distances, etc. Thoughts?