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[APD] Water and "electrolytes"
An exchange on APD, earlier, with Bob Dixon, made me realize that we
spend lots of words on hardness, pH, osmosis and tds, but we rarely
discuss the cellular function of electrolytes. I'd love to learn more
about them and their operation.
Medical types usually define blood electrolytes as Ca++, Mg++, Na+, and
K+. The first two are divalent ions that contribute to hardness and the
others are monovalent and not involved in GH at all (i.e., don't make
soap scum form). All are important to transporting "stuff" across cell
walls. I think their ratios are often more important than absolute quantity.
I had seen several fish stores killing Discus by trying to keep them in
pure RO water, which surprised me, but the problems really came home to
me when I moved to Modesto, which had ridiculously soft water after my
lush and healthy 300 ppm (200 ppm hardness) water in Fremont.
At 50 ppm it had 0 degrees of both General and Carbonate hardness. The
main ions were from silicates and (maybe) aluminum. I killed much of my
Java Moss and nearly killed some nice killifish before I caught on.
"Dead Soft" indeed!
With such low tds, I reasoned a bit of salt would reduce the osmotic
pressure across the cell barriers and hence reduce strain on fish and
Wrong! My Java Moss, which is a salt-loving estuarine plant in many
places, bit the dust (well, it melted and turned brown), fast. Jave Fern
(another salt-tolerant plant) was also in obvious distress. The fish
didn't say much, but they, too were obviously not very happy.
I added a bit of Seachem's "Equilibrium" and got a turnaround so rapid
that the plants looked better the very next day! Somewhere I had
remembered a bit of trivia that divalent and monvalent ions were
essential to many cell transport processes, and that bit of trivia saved
Within weeks, I had lush plant growth in all my tanks, and the fish were
happy and breeding well, again.
Two lessons I learned from this:
1) Salt, sodium chloride, can be deadly if there is no Ca or Mg to go
with it to balance the electrolytes, and
2) Low tds water isn't the "to-die-for" water that some fishkeepers
yearn for. I have done best with true rainforest fishes at 80-120 ppm
tds, with about 2/3 of that from Ca/Mg hardness. Most plants love it if
the electrolytes are even roughly in balance.
Barry Cooper went through a similar process when he moved from Cornell
NY to OR. We corresponded on it and I'm not sure what parts were whose
ideas. As a veterinary pathologist, I suspect he made the larger
contribution, but I rely on my aging memory to avoid giving him too much
credit. :-) We were busy discovering much the same things at about the
Wright Huntley - Rt. 001 Box K36, Bishop CA 93514 - whuntley at verizon_net
Eschew obfuscation and bloviation!
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