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Re: Problem levels of Na and SO4 from water analysis
On Fri, 8 Dec 2000, Aaron Ivers wrote:
> My tap water contains ~40 mg/L of sulphate. One particular response I
> received suggested this level was quite high and could be bad for my
> substrate in the long run (by turning into sulphite). While I understand
> that plants use considerable amounts of sulphur, I can't help but wonder if
> this concentration, plus the sulphate added by my K2SO4 additions, maybe
> overkill. I'm thinking I should switch to KCl to minimize the sulphate
> levels and increase my low chloride levels (0.6 mg/L) at the same time. Any
Your sulfate is not a problem. My tap water carries 115 mg/l of sulfate
and I have substrates that are much as 12 years old. It isn't a problem.
Given your low chloride concentration I would use KCl just to get a more
balanced composition. That's just a matter of balance; I don't think
there's any problem with the low chloride numbers.
> BTW, I'm fighting a blue-green algae problem on top of my Profile/gravel
> substrate (any link to high sulphates?).
None I know of.
> I have 48 mg/L of calcium, 13 mg/L of magnesium, 2.2 mg/L of sodium and I
> supplement the low potassium (0.6 mg/L) with K2SO4 to match the magnesium
> level. The same person who responded above also suggested my sodium level
> (2.16 mg/L) was low. When I asked what level this person suggested they
> responded that their water contained 6.5 mg/L of sodium.
Plants don't use sodium and to the best of my knowledge should grow fine
in sodium-free water. There's nothing wrong with your sodium level.
> This got me thinking about the cation ratios found in The Optimum Aquarium
> (sodium dominates the cations ratio while chloride dominates the anions
> ratio). I then read in the archives that the cation ratio isn't important,
> but can anyone suggest how much sodium and chloride should be maintained in
> a planted aquarium? Should I be adding NaCl?
You can add salt if you want. It won't hurt anything, but none of your
plants will need it. Sodium isn't used by plants and at high levels can
interfere with plant uptake of other nutrients. Chloride is used in trace
amounts and I think even the small amount you do have should be
As I said, given the sulfate in your water I would dose with KCl just to
balance things out. I like balance.
Judging from the analysis, I'd say you have excellent (if somewhat
unusual) water. You should find something else to worry about.