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Re: Aquatic Plants Digest V3 #1070
In order to increase hardness to a certain point without paying too much
attentuion to the process, one has to add only enough CaCO3 that if
everything dissolves and without other interactions, one gets the
desired calcium concentration:
Volume of water (in Liters) x 0.0178 = weight (in grams) of CaCO3 needed
to raise hardness by 1 "German degree".
In your case it is 100 x 3.8 x 0.0178 = 6.8 g (about 1/4 oz)
So, add about 1 ounce of marble chips and, after a while, you should get
about 4 oGH hardness. When you get a chance, measure hardness and see
whether additional treatment is necessary.
In an actual working aquarium there are so many (unknown) variables,
that one just has to measure the result.
> Date: Thu, 3 Jun 1999 15:27:43 -0700
> From: "Mortimer Snerd" <n9720235 at cc_wwu.edu>
> Subject: Re: Calcium issues
> This is a useful and well timed conversation for me, as I suspect I'm in the
> same boat calcium-wise as Tom Brennan, with my super-soft NW water. OK, I
> get saturation point. My question is this: How do I figure out how much in
> the way of marble chips or oyster shell or whatever do I stick in the sump
> of my 100 gallon to raise my calcium level a bit, but not bump the hardness
> over about 4 or 5 degrees (Sorry about using degrees rather than ppm, but I
> use a Sera test kit, so degrees are easier for me to think in). The problem
> I have is that I'm in the final stages of finishing my Bachelor's degree, so
> I'm running around like a crazy person and don't have a lot of time to do
> water tests, sleep, eat, breathe, etc. I also use CO2 injection with a
> Sandpoint controller, so my pH will stay at 6.8 until my water reaches
> stupid-hard levels, unless I put time into paying attention to measuring it.
> I'd really like to be able to put some chips in the tanks and forget about
> them; is this a possibility?
> Justin Collins, in Bellingham WA, where its finally sunny!
> > Date: Thu, 03 Jun 1999 10:51:33 +0000
> > From: George Slusarczuk <yurko at warwick_net>
> > Subject: Re: Aquatic Plants Digest V3 #1068
> > Hello Tom,
> > You just had to pick a question that does NOT have a clear cut answer!
> > :-))
> > The *saturation* point is when no more of a substance dissolves, or
> > rather when the substance in solution is in an equilibrium with the
> > solid phase, out of solution.
> > The *solubility* of calcium carbonate [CaCO3] in *pure* water is only
> > about 17 ppm (i.e. about 1 "German degree"). It is a well known fact,
> > that calcium BIcarbonate [Ca(HCO3)2] is much more soluble in water than
> > calcium carbonate. Calcium bicarbonate is unstable, exists only in
> > solution, one can not isolate it & put in a bottle. The way one prepares
> > it, is to add CO2 to the water which is in contact with excess solid
> > CaCO3. The CO2 (actually carbonic acid, H2CO3) reacts with the calcium
> > carbonate in solution, forming the bicarbonate, and shifts the
> > equilibrium, allowing more solid calcium carbonate to dissolve... and so
> > on.
> > If enough CO2 is present, a lot of CaCO3 can dissolve. My well water has
> > 430 ppm CaCO3 hardness. I have heard of places with REALLY hard water
> > ("liquid rock") with over 1,000 ppm CaCO3. So, depending upon available
> > CO2, the calcium concentration will vary.
> > Most solid-liquid reactions are slow. In an aquarium with fish one does
> > not want to change the water parameters rapidly -- it puts stress on
> > fish, might even kill them. So, a slow coming to equilibrium, in my
> > book, is an advantage: Just place some marble chips (in a sock) in your
> > filter, and forget about it for several days. Take out the sock when you
> > reach the target hardness -- that's all there is to it!
> > Adding calcium as CaCO3, vs. CaCl2 or Ca(NO3)2 has the further advantage
> > that you are also increasing the alkalinity (KH) and *buffering
> > capacity* -- the ability of the system to resist changes in pH.
> > If you have further questions, feel free to ask.
> > Best,
> > George