I recently spoke to a Seachem Rep about using Limewater compared to Reef Advantage Calcium ...
"Kalkwasser is a difficult supplement to get right. It will increase your pH. But a high pH encourages precipitation. So usually your magnesium level drops. Magnesium is what keeps your calcium and alkalinity from precipitating out at normal levels. It can also precipitate phosphates, but you will lose calcium. If you drip kalkwasser at night if can combine with CO2 (provided you have enough) and create alkalinity. So it does have the potential to be a unitary supplement. Another problem that occurs is that you need to evaporate enough water so that you can drip enough Kalkwasser. Kalkwasser only raises your calcium a small amount 1 gallon of Kalkwasser added to 40 gallons of water will only raise your calcium 24 mg/L. So as you can see there are many pros and cons to using kalkwasser. Perhaps a few tests on your tank will help you to see how you could improve this system. I would recommend magnesium, calcium, and alkalinity."
Personally I use Reef Salt, Reef Buffer, & Reef Advantage Calcium for LR results that look like this ...
Reef Salt will help you start out with the correct buffer, Reef Buffer will bring pH up to 8.3 and raise alkalinity and Reef Advantage Calcium is a ionic calcium supplement that raises your calcium levels quickly along with proportionate amounts of magnesium and strontium.