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The "best" way to measure calcium and other minerals

At the moment you will find that most books and a lot of websites quote
units of degrees of general hardness (GH) when referring to the
appropriate measurements of mineral content in aquarium water for
plants. For SHAME!!!

While GH has some meaning for people washing clothes and steam engine
operators, it has little to do with a meaningful measurement of
minerals. The units of GH are entirely contrived and you will always
have to apply some conversion to mg/L or molar concentration in order to
calculate the appropriate concentrations of minerals.

If you get a water analysis you will find that the units for
concentration of all mineral ions are always quoted in mg/L or parts per
million. This is as it should be because the engineering, chemical,
scientific and industrial community has adopted a uniform set of
measures for such things.

The problem in the aquarium industry is that Joe Q Public, the consumer
is relatively ignorant of what it is that he should be shopping for when
he looks for products and test kits. Since the literature refers to GH
and KH and he only finds test kits calibrated in these arcane unit, he
continues to BUY those test kits.

It's not that the aquarium industry wouldn't LIKE to get with the 20th
century (now that its nearly over) but their products are entirely
oriented towards what the public thinks it wants. So if the great
unwashed masses (pun intended), thinks that they need test kits which
are suitable for doing laundry, then that's what the industry is going
to provide them with.

What can WE do about it? I'm a pragmatist so I'm going to be honest with
you: precious little. I can't foresee the aquarium industry changing
because a handful of APDers say they should.

But I have some suggestions:

1) We can talk about it and try to agree what are the most appropriate
and USEFUL measures for mineral content in water.

2) We can lobby the aquarium industry to provide us with USEFUL test
kits and products. By the way, I strongly suspect that all of the big
aquarium product companies DO have folks who read the APD just to keep
an ear to the ground.

3) We can hope that the people who WRITE aquarium literature and
websites read the APD and agree that its time for a change and we stop
using units for SOAP to measure minerals in aquariums.

I know on my website I use measures like cups, teaspoons and GH for
specifying amounts of chemicals. Mea culpa. I plead guilty. My excuse is
that I'm only pandering to the whims of the public who only have access
to such measures and tools. (gosh, I feel so CHEAP and TAWDRY!)

I suppose I should join the 21st century and provide the measures in
metric. I've deliberately NOT quoted both measures because it only seems
to confuse folks.

What are the chances of having an impact? hmmpfff - we can't even seem
to get folks to stop posting HTML onto the APD; small chance there'll be
a consensus amoung any of us except for the botanists, chemists,
limnologists and the free radicals like me. (pun intended)

Another point while I'm on my SOAP box; those of you who are using the
rule of thumb that 1 tsp of CaCO3 raises the GH of 10 gallons of water
by 2 degrees GH should be aware that this method has an error factor of
2 or 3. One tsp could raise the GH by as much as 6 units of GH depending
upon how fluffy or fine the calcium carbonate powder is ground. Since
calcium is required in such large amounts, its probably a harmless

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!