1994 Dodge Spirit charging system

I was recently told that my water pump needs to be replaced due to excessive anti-freeze leakage. I purcahsed a name brand stop leak which so far has done the job. Though I plan on replacing the water pump very soon, my question for you is would this have a direct bearing on my charging system. Now when I drive my car, when the tempature guage runs on the cool side, I notice my battery guage lowers to above 8. I was told my alternator needs to be replaced. Though my car needs a lot of work it is the only car I have thank you john young