ALKALINITY
Alkalinity plays a major role in skeletal growth of your corals, keeping it stable will improve your reef tank and keep your inhabitants happy!
Recommend alkalinity levels between 7.5-9dkh
DIY alkalinity mix for your saltwater aquarium
Recipe 1
Use if your reef tank pH is normal or low. Most will end up choosing this recipe over Recipe 2. It will raise pH like most commercial two-part additives sold on the market.
If you are using limewater (kalkwasser) and the aquarium is at pH 8.4 or above, its recommended to use Recipe 2.
Recipe 2
Use in your reef tank if pH is on the high side (above 8.3).
If you are using kalkwasser and the aquarium is at pH 8.4 or over, this recipe is likely a good starting point. It is half the strength of Recipe 1.
For both recipes it is best to use kitchen scales with a 5kg capacity.
INSTRUCTIONS
Recipe 1, Alkalinity
Causes pH raising effects, generally good for most saltwater reef tanks.
Spread the Sodium Bicarbonate (594 grams or about 2 ¼ cups) on a baking tray and heat in oven at 200°C for one hour (longer is not an issue) to drive off water and carbon dioxide. After heating the total weight will be less due to driving off the excess water.
Dissolve the Sodium Bicarbonate in enough water to make 3.78L (1 gallon ). This is total volume, place your mixing container on scales and zero the scales. Add all the Sodium Bicarbonate then add RODI water until your scales show a total of 3.78kg (1 gallon).
Warming the water prior to 35 degrees Celsius will help it dissolve faster. This solution will contain about 1,900 meq/L of alkalinity (5,300 dKH).
Added as frequently as necessary in a high flow area to maintain alkalinity.
Recipe 2, Alkalinity
NO BAKING REQUIRED. LOWERS PH
Dissolve 297 grams of baking soda (about 1 1/8 cups) in enough water to make 3.78L total (1 gallon). To dissolves may require a lot of mixing. Warming it will help dissolve faster. This solution will contain about 950 meq/L of alkalinity (2660 dKH). Be sure to NOT use baking powder.
Always use food grade ingredients or higher.
RESOURCES AND REFERENCES
https://reef.diesyst.com/chemcalc/chemcalc.html
(select your recipe either Randy's Recipe 1 or 2 in the list and calculate your dosage!)
https://www.hamzasreef.com/Contents/Calculators/AlkConversion.php
(handy calculator for all things reefing)
https://reefkeeping.com/issues/2006-02/rhf/index.php
(original Randy's Recipe instructions by Randy Holmes Farley)