Calcium & Alk. Additives - What's best?

[Aquattro]

Marie, my comments were based on my old tank, my new one isn't growed up enough yet

My reactor holds about 18 pounds of media, so I don't need to change it that often. I find the first annual change is just to remove the finer sludge, it tends to slow the flow after 4 or 5 months.
Still, I never used a pound/week, even at it's peak of growth.