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Re: Calcium additions

On Tue, 1 Jun 1999, Aquatic Plants Digest wrote:

> > When plants do suffer a
> > calcium shortage they show it by producing stunted, gnarled new growth.
> > Some plants are more sensitive to the absence of calcium then others, so
> > only one or two plants in a tank are likely to show the early stages of a
> > calcium shortage.
> This is very misleading! Calcium _deficiency_ shows as deformed growth
> but a calcium shortage will be evident as slow growth rates for many
> plants especially Echinodorus species. I believe that there is a range
> of symptoms of calcium shortage which become more extreme as the calcium
> concentration goes lower.

Are you quite sure about this?  While I've seen several plants drop into
severe calcium deficiency I don't recall that they went through a
phase of slow growth prior to the onset when conditions were marginal.  In
fact the most recent onset (in H. corymbosa) came at a time of somewhat
elevated growth rates.

I presume (speculate? theorize?) that the plants start producing deformed
new growth precisely because they don't slow their growth when calcium
levels are too low.  If they could regulate their growth rate to match low
calcium levels, then growth would simply slow down to a pace where the
plant could get adequate calcium supplies to meet its needs, and there
would be no deformed growth.

Roger Miller