It seems like until recently everybody used to the 6.2. I could be wrong on that though. I'm relatively new at all this. I don't think you necessarily need to buy both. I think people have done just fine with the 6.2. I sure as heck can't buy both, Hill I'm still paying off the first one. if they come out with a third version that everybody says is wonderful I will just screamSorry, you quoted before I had edited post. Typing on an iPhone is bad
I've looked for a conversion, and have asked Tom. But apparently there is no such thing that I/we have found.
I bought a 6.2 because it's easier to track uvb decay. But it isn't used often for determining if the bulbs are giving the correct levels. I guess that's how they get you to buy both.