We have found that by using SeaChems Reef Builder and Reef Advantage in alternating doses in our make-up water we have had no trouble keeping both the calcium and alkalinity at the proper levels for rapid coralline growth. This simple method of treating our make-up water also keeps the strontium level in our grow out tanks high enough for the coralline algae to thrive. This picture shows tank grown aragonite live rocks that are 8 weeks old. The Coraline algae has started to cover the aragonite. You must keep the Phosphate level in the live rock grow out tank very low.
Protein skimming is important in the grow out tanks because it controls phosphate.
Make-up water can be a source of phosphate. You may need a reverse osmosis or deionization system if your water source has phosphates. Feeding is the most common source of high phosphate levels. We use a phosphate removing filter in tanks that are not producing coralline algae fast enough. We keep the lights on for 14 hours and the Coraline algae grows on every part of the rock that is exposed to the light.