quoted from wwm
Dry Calcium (Calcium hydroxide: AKA “Kalkwasser”): In summation, one of the absolute best supplements to dose calcium in aquaria with a long list of benefits and few disadvantages. Easy to use, but easy to abuse. Follow dosing protocol strictly.
Advantage: A potent and direct method of providing calcium
Caustic nature increases pH and indirectly supports Alkalinity by tempering acids that would otherwise burden the buffer pool
Is self-purifying by virtue of its highly caustic nature. Most impurities commonly found in the raw reagent precipitate out. Aids the neutralizing precipitation of nuisance phosphate in aquaria. This is a tremendous advantage over all other methods of dosing.
Improves skimmer performance (saponification).
Dosing at night tempers pH swings from inevitable drop from respiration by photosynthetic dynamics.
No negative, residual by-product of its use (like accumulating Chloride ions with “Liquid calcium” products)
A long-term calcium supplement
Disadvantage: High pH limits supplementation to dosing at night or in increments
that will not raise pH suddenly by more than .2
Dosing by the commonly recommended supersaturated solutions is tedious and messy (instead, see “Slurry method” in the Book of Coral Propagation, Volume 1 for a tidy and succinct dosing method).
Can be dangerous or stressful to system if misapplied
Here are my personal steps in how i make my mix,
Step 1 take your milk jug and fill 3/4 way full of water.
Step 2 Add 1/4 teaspoon kalk powder.
Step 3 shake shake shake
Step 4 Let the milk jug set for about 8-12 hours. to allow for the mixture to cure.
Step 5 Take your doseing unit and pour from your milk jug the clear liquid on top, try not to slush around your jug. If you look you will see a white milky substance at the bottom of the jug. You do not want this milky stuff. You only want the clear liquid.
Step 6 Drip into your tank at a rate of about 1 drop every 15 secs. For a 1200ml container 14 drops every 43 seconds will empty it in 24 hours. I drip slower as to drip 24/7 for a week. I only drip every other week in between water changes.
I hope i was helpfull have fun.