Yes, I think that is right.  I don’t think aldosterone production is COMPLETLY independent of the Hypothalamic Pituitary Axis, which controls ACTH and cortisol production, but I think the effects are generally considered to be minimal. 

 

Aldosterone secretion is mostly mediated by the Renin-Angiotensin axis.  Renin and angiotensin are hormones produced by the kidneys, in response to changes in blood pressure and blood volume.