This is what I use daily,very easy to dose in my nanocube.
CaribSea: Araga Milk
In closed systems, carbonate is consumed both as a buffer to neutralize
organic acids, and combines with calcium for coral and coralline algae growth. The aragonite in aragaMILK, TM supplies calcium and other major and minor trace elements plus time release carbonate ions in a safe balanced form. Now “Improved Formula” aragaMILK, TM also contains an additional bicarbonate buffer to meet the immediate buffering demands of excess organic acids. aragaMILK, TM is a great way to safely “push” normal seawater values of calcium and
alkalinity to accelerate coral and coralline algae growth.
The perfect alkalinity booster because...
aragaMILK, TM has a full pound of buffer in every 16 fluid ounce bottle. This buffer comes in two forms: a bicarbonate for immediate response, plus carbonate from aragonite. This second form makes for a safer, time-release buffer, over 2-3 days, for long term security without the wild pH swings that can stress
your tank inhabitants.