I also have a well, don't use water conditioner either. UV sterilizer is not necessary IMO. Our well has failed bacteria tests before and these are pretty meaningless to the fish (coliiform) because its gonna be present in the aquaria anyway. Our retests always come back safe. Well water should be tested once a year for drinking water. We get our tests from the local court house/gov building. Cost depends on what you test for. The kits are free, its simply a jar and order form. You take a water sample fill out what you want tested, cost is on the order form, you mail it with a check.
City/town water tastes icky and I won't buy bottled. Well water is the best.