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I have had a problem with older leaves getting algae and/or falling off. Aside from telling me to increase co2, the other reason I've heard of this happening is possibly a deficiency in Ca or Mg. I was able to get the following readings from the water plant:

Average 38 mg/l Ca
12 mg/l Mg

Is this enough of these nutrients to prevent deficiency? The info I've seen only gives degrees hardness in GH.

(As an aside, I was suprised to learn the water averages 1.9 mg/l PO4!!!)
It looks like they are reporting as ppm Ca and ppm Mg, NOT as ppm CaCO3 equivalent (which would be divided by 17.9 to get dGH). SO:

38mg/l Ca * 100gCaCO3/40.0g Ca = 95 ppm CaCO3 equivalent/17.9 = 5.3 dGH from calcium alone.

12mg/l Mg * 100gCaCO3/24.3g Mg = 49 ppm CaCO3 equivalent/17.9 = 2.8 dGH from magnesium alone.

So you should measure 8dGH (5.3 + 2.8)- and there is plenty of each element there for your plants.

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