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tap water phosphates and nitrates
On visiting me recently my parents were impressed with my tank and would
love to have one. I have recently obtained a water report from my parents
local water provider - in London, England. I am trying to ascertain if it
is possible for them to grow plants successfully. This is a list of the
relevant measurements:
Measure mg/l
pH 7.9
Hardness 67.2
Alkalinity 144
Calcium 62.1
Magnesium 2.7
Phosphorus 1.1
Nitrite 0.01
sodium 16.4
Nitrate 33.81
Iron 0.047
copper 0.023
Manganese 0.002
zinc 0.014
Boron 0.041
Having read this I became particularly concerned with the level of nitrates
(33ppm) and Phosphates (1.1ppm) in the water supply. I imagine that a tank
that maintained these levels of nitrate and phosphate would have algae
problems. The other thing I thought was, with levels this high in the tap
water, what would be the point of a water change?.
I have been spoiled on Seattle's tabla rosa water. I have to add PMDD to
my tanks. Evidently plants do use phosphates and nitrates, however, would
they be used fast enough to allow regular water changes.
Using the most recent PMDD ratios I am aware of (from Sunday, April 13,
1997):
in 500ml H2O.
1 tbs. trace element mix,
1 tbs. Epsom salts,
1 tbs. KNO3,
2 tbs. K2SO4
and assuming the plants use nothing, you would have to add 5-6 ml per day
to maintain 30ppm Nitrate in a 55gal tank (25% water change every 14 days).
Does anyone find themselves using these amounts of PMDD to maintain a
tested level of NO3 below 10ppm?
In Seattle there are no nitrates or phosphates in the tap water. I add
nitrates to compensate, however I do not add phosphates. I understand the
acceptable level for phosphates is under 0.1 ppm. The prospect of adding
water that contains ten times that level kind of fills me with dread. A
water change of 25% would push up the concentration to .25ppm (assuming no
phosphates present before water change). For Sears and Conlin an addition
of 0.1 ppm imediately caused an increase in algae. There is a deal of
phosphophobia on the list, but as I understand it people are adding some
phosphate some of the time, I would like to find out how often and how
much. What are the smallest changes you can get away with?. If I changed
5% of the water once a week (only pushing phosphates up by 0.05ppm) would
other water parameters become out of balance in the long term?. Failing
this are there any other inexpensive methods of removing phosphate from the
water?
Does any one else have water this bad?. Thanks.
David Brooks