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Re: Equilibrium, Ca and Mg levels
If I recall, the right molar ratio of Ca to Mg is 3:1 but 2:1 should
also be just fine. It's probably better to err on the high side of
calcium.
The reason you may find a high ratio of Mg to Ca in nutrient supplements
is that its not possible to dissolve very much Ca in combination with
typical anion base pairs (hope I said that right) such as sulphate or
carbonate. You still need a significant amount of Mg in proportion to
the other nutrients in supplements (just as in PMDD) so the assumption
is that there is already lots of Ca dissolved in your water. For those
of us with soft water, we need to add CaCO3 (or similar calcium source)
to our water at water change time. Even if I'm just topping up
evaporation losses, without removing water, I add calcium every few
months since it is used up.
When you see poor growth rates and stunted tips in fast growing plants,
you should immediately suspect a shortage of calcium. Sometimes those
with hard water still don't have enough calcium because the hardness may
be sodium/magnesium/potassium paired with carbonate or sulphate!! Those
hardness test kits are just not as accurate as the analysis available
from your water utility for free. I encourage folks strongly to take
advantage of that and to inquire about seasonal variations. Sometimes it
varies very little (as here in greater Vancouver) but sometimes they
switch reservoirs in some municipalities and it behooves you to know
when that happens.
--
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!!!