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Re: Seasonal changes in Ludwigia x. repens

David Wittaker writes:

> I'm also interested to know if those of you who are using
>  calcium chloride, as opposed to calcium carbonate or
>  bicarbonate to supply calcium, have run into any problems.
>  I'm discontinuing its use for now, but I have yet to devise
>  a good method of dissolving powdered dolomite without
>  clouding the tank.

One of my projects for next summer is to build a CO2 generator that will have
two bottles.  The upper one will have HCl atg about 8-10% solution, and a
controlled siphon drip down to the lower one, which will contain dolomite.
The CO2 will then be vented to the tank.  The other products of the reaction
will be water and CaCl2.  If you used Nitric acid instead of hydrocloric, it
would produce calcium nitrate instead of calcium chloride.  You could then use
the calcium nitrate to supply both calcium and nitrogen our tank.  Or any
other acid that would generate an acceptable calcium salt could be used, and
that salt then used to dose for calcium.  Just a thought.

Then again, last year as part of my daughter's fifth grade science project, we
put dolomite inside the end of a nylon stocking, stuck that into a box filter,
and let the water harden by naturally and slowly dissolving the dolomite.  A
little dolomite came out at first, but after a day, it was all better.  A
small box filter with a slow flow rate would probably provide a continuous
supply of calcium suitable for a big tank.  And if you then used some kind of
pH adjuster to keep the pH down, it would react with the carbonate and give
you CO2.

Bob Dixon