Is calcium carbonate buildup on reservoir walls a problem?

[capman]

Randy,

Thanks for the useful, interesting article.

I have a followup question for you:

In at least one well-known book I have read the suggestion that calcium carbonate precipitate in the reservoir might tend to reduce the concentration of limewater because the crystals can serve as seeds for further precipitation of calcium carbonate. I'm wondering whether the inevitable buildup of calcium carbonate that occurs on the walls of limewater reservoirs (as well as the calcium carbonate particles that build up in the bottom sediment along with the undissolved excess calcium hydroxide) affects the concentration of limewater in the reservoir? If there is any significant effect, then this is not a trivial matter for those of us using large limewater reservoirs, since thoroughly cleaning the calcium carbonate deposts off the interior walls of a very large reservoir can be awkward.

It always seems like my tank pH is much higher (suggesting stronger limewater) right after the reservoir is throughly cleaned.

Thanks,
Bill

[Randy Holmes-Farley]

In at least one well-known book I have read the suggestion that calcium carbonate precipitate in the reservoir might tend to reduce the concentration of limewater because the crystals can serve as seeds for further precipitation of calcium carbonate.

No, I don't believe that to be important. This assumes that the limewater will stay supersaturated with respect to calcium carbonate, and I don't believe that will happen at a pH that high and with the very high liklihood of other seeds around (like solid lime). It certainly has zero impact on the saturation of the lime itself.

The presence of such solids might even be good:

http://www.advancedaquarist.com/issues/may2003/chem.htm