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Re:Water Chemistry
Walter Klockers wrote, Oct. 8:
>
>....I checked my tap water tonight, with the following results:
>
>pH - 6.6
>KH - 3
>GH - 60 ppm
>CO2 - above 15 mg/l (TetraTest)
>
>I was surprised how soft the water was. Any comments about the water out
>of my tap that might be helpful? Thank you.
>
Your water could be a lot worse. Assuming that your ppm value is expressed
as CaCO3 obtained by multiplying GH in degrees by 17.8, you must have about
three to four degrees GH. Your tap water sounds a lot like the tapwater I
get at home, which is reservoir water with some lime added by the water
treatment plant so that it won't be so soft it corrodes the pipes. The CO2
content doesn't mean much if it was taken from water just out of the tap,
because the water, after standing a while, gets in equilibrium with the CO2
in the atmosphere, and I am pretty sure it won't have 15 mg/l.
Magnesium is one possible concern. If they added lime to the water, your
GH will be almost all due to the calcium from the lime, and there may be
very little magnesium. You should not count on the fish food to be an
adequate source of Mg. Yellowing of the older leaves where the edges are
yellow and the midrib is still green is characteristic of magnesium
deficiency. If you see anything like that try adding some magnesium
sulfate, approximately 1 cc of 1 molar MgSo4 per gallon. Calcium can also
be a concern, especially if you have snails to keep soft attached types of
algae under control. A bunch of snails can remove calcium quite
efficiently from the water and can lower the content to the point where the
plants become deficient. I have seen this happen even with hard water where
I didn't make any water changes for a long time. You can keep the Ca level
up with regular water changes or you can regularly add small amounts of
powdered limestone or agricultural lime. A lot of people think adding lime
is too dangerous, because it is calcium oxide, rather than calcium
carbonate, but I have found that adding about a half teaspoon or so to a 15
gallon tank doesn't change the pH noticably and takes several weeks to
mostly dissolve, which is only slightly faster than it takes ground
limestone to mostly dissolve. Calcium deficiency symptoms are production
of smaller, distorted leaves, often with reduced leaf area and white
streaks or edges. Worse Ca deficiency symptoms are smal, white, twisted
stumps for leaves, followed by death of the meristematic (growth) areas of
shoot and root and, thus, no new shoot or root growth.
Cuttings that are getting established are more sensitive to low calcium
than plants with well established root systems. When I am getting newly
planted plants started I have to be sure to add some lime to the water
because most of my tanks are at the school where I teach, and the water
there has no measurable GH, although it has a rather high KH of 9 degrees,
which turns out to be entirely sodium bicarbonate---rather odd water that
it has taken me a long time to understand. I finally got the picture when
I added a bunch of Ceratophyllum to a tank freshly filled with aged tap
water, and the plant developed calcium deficiency symptoms (the growing
tips turned white and then fell off) in four days. I added some lime, and
the plant recovered, putting out normal-looking new growth in only two
days.
Paul Krombholz in Jackson, Mississippi where clouds and moisture are
increasing. Could there be some rain on the way?