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[APD] Re: Nutrient Dosing
Tom Wood asked:
"A few excerpts for the Green Water Treatment Plant (GWTP)
In mg/L
Calcium 12
Magnesium 15
Total Hardness
(as CaCO3) 93
Total Alkalinity 66
(as CaCO3)
Can some of the chemists here decipher what this means? I don't add
Magnesium, but should I?"
You don't need to add either Calcium or Magnesium nor adjst the Alkalinity
given those readings. You do know that the reported results as CaCO3 doesn't
necessarily mean that CaCO3 is the sole diatomic cation responsible for the
water's hardness. Any +2 cation will contribute to water hardness, but Ca+2
and Mg+2 are the most common. The readings are reported as ppm (mg/l) CaCO3
purely as convention.
"My newly planted H. difformis has white veins and rather spindly new
growth. The new leaves also don't have the deeply cut ridges characteristic
of this plant. I'm assuming Fe deficiency here, since the iron was nearly
undetectable when the plants first went in. Current iron levels are at 0.1
ppm."
Try cranking up the Fe levels. Are you using a balanced micronutrient mix or
dosing iron by itself?
"My h. difformis started doing better when I cut back on K2SO4, but I'm not
sure of a connection."
I doubt that K2SO4 was a problem. Potassium is relatively benign as is SO4.
Both Potassium and Sulphur are macronutrients and they don't usually cause
much of a problem if present slightly in excess of the plant's needs.
How is your lighting and CO2 levels?
James Purchase
Toronto
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