Glad you got it fixed. Just remember though, just because a belt is tight, it does not mean that it is OK. If you had gotten something on it that was causing it to slip, it could be tight and still slip. As far as the
antifreeze comment, it should not cause a problem as the coils in the alt, are sealed, but if there was any break in the seal (you wouldn't really be able to tell) then yes that could cause problems with the alt.