Randy Holmes-Farley Recipe #1 calcium part (Part 1)
calcium
CaCl2·2H2O
Manufacturer data
As an Amazon Associate we earn from qualifying purchases. Buying through these links costs you nothing extra and helps keep the app free.
What one dose does
PARAMETER
1 ml / 100 L
Calcium
+0.37 ppm
To raise calcium by 20 ppm in 100 L: 54.1 ml.
How it’s used
500 g (about 2.5 cups) Dowflake-type CaCl2·2H2O made up to 1 US gal final volume -> ~37,000 ppm Ca (published). Check: pure dihydrate gives 500 x 0.2726 / 3.785 L = 36,010 mg/L; Dowflake at 77-80% CaCl2 gives ~36,700-38,100 mg/L. Starting doses (Recipe #1): 0.1-1 ml per gallon of tank water per day depending on demand; dose equal volumes of Part 1 and Part 2.
Cautions
• Never dose the calcium part and the alkalinity part at the same spot/time or premix them; CaCO3 precipitates.
• Keep calcium increases <=50 ppm/day for large corrections (BRS guidance).
• Two-part dosing adds NaCl as a by-product (CaCl2 + Na2CO3 -> CaCO3 + 2 NaCl); monitor salinity and do periodic water changes.
• Ice-melt products vary in purity and hydration; unknown brands are untested for heavy metals.
• Hydration state changes Ca per gram: anhydrous 36.1% Ca, dihydrate 27.3%, hexahydrate 18.3%.