Why do you think it's too much calcium? The purpling symptoms sound more like phosphorus deficiency. Check out the link below, but here's the excerpt on phosphorus:

"Phosphorus - P - Deficiency
Lower leaves and stems [I've seen it on middle and upper-middle leaves, too.]

"First sign of deficiency is stunted plant growth, and leaves become darker green. Then, lower leaves and stems may develop red or purple coloration. In worst cases, lower leaf chlorosis [yellowing] and necrosis [death] occurs. Slight phosphorus deficiency is used in plug production to reduce size and darken leaves. In most cases P, deficiency is not common."

When they say that P deficiency is not common, they are talking about in crop soils, not potted plants that depend on you for their P. And even in plain old dirt, you can see P deficiency fairly often, at least I have. I think that sometimes, it indicates that you've given the plant plenty of nitrogen and/or potassium, and all that rank growth makes it P-starved.

Pics would help nail it down. What grow media and fertilizer have you used?

Deficiency and Toxicity Symptoms