In the report there are two lines for hardness and they are
> Hardness, Calcium (as CaCO3) 24
> Hardness, Total (as CaCO3) 28
Plus it lists magnesium seperately
> Magnesium 1.5
All values are mg/L.

What is the difference between the first two?

Thank you,

-Steve
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For most purposes, magnesium hardness is the difference between calcium hardness and total hardness. To be strictly formal that difference could include some hardness caused by strontium and barium, but those are relatively rare elements.

Your report indicates that there should be about 4 ppm of hardness (as CaCO3) caused by magnesium. 4 ppm of magnesium hardness is equivalent to 1 ppm of magnesium. That's a bit different from the 1.5 ppm of magnesium that they report. It's hard to say what might cause the difference. The conclusion is the same either way. You don't have much magnesium in your water. Not much calcium either, for that matter.


Roger Miller

 

So the total hardness above would be what the AP hardness kit measures, right?

I supplement Mg and Ca at water changes. Even with the supplements my Vals now make a good foreground plant.

-Steve
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Yep. The AP kit and most other hobby kits should read total hardness. Hach and (I think) LaMotte makes kits that can read calcium hardness but those kits aren't in common use.

Are you dosing with phosphorus? A phosphorus deficiency can cause vals to grow about 2 inches high. Nice and green, but 2 inches high.


Roger Miller

 

Yes I dose P. I add a total of 10ml of Seachem P over the course of the week. That adds about 0.5ppm of P per week.

-Steve
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See whether leaving out the magnesium for two months un-stunts your Vallisneria.

 

If I don't add Mg then I get little yellow spots all over my java fern, anubias, and poor sword growth. I have read that vals like hard water so perhaps they don't want to grow because of my soft water. I don't know, its just a working hypothesis.

For most of the year I wasn't adding Mg and the vals didn't grow but I have been dosing heavily on the K. I will be changing that soon.

I have been using Seachem Equilibrium for Ca, and K. Equilibrium adds a lot of K, at least 30ppm per 1tablespoon dose for my tank. That plus the K from KNO3 (about 15ppm per week) could be pushing my K way up. Not sure if this means anything but I thought I read some people write that high K can interfere with the uptake of Ca. I have been using Equilibrium just becuase I had a bottle of it. I plan to go buy some CaCl so I can individually dose Ca, K, and Mg. Honestly I have not really cared about the val growth. Right now all the other plants are doing great (except for algae on my anubias).

-Steve
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