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