Hello valerie a, and welcome to the forum,
While some well water can be very tricky to work with, you probably would still be better off using your water from the tap. Make sure you use a water conditioner that neutralizes, chlorine, chloramines and Heavy Metals.
Add the conditioner to any tap water before putting the water in the tank.
This applies to water changes and top offs also.
If you do decide to use your tap water, do not change all the water at one time. Other wise you will shock your fish.
And if you really want to be on the safe side, use a liquid test kit and test your tap water. You will need the test kit any way for testing your tank water.
Also are you using any type of softener or conditioning system on your well water?