For LR I assume you want to grow coraline algae. Then you need calcium. There are many different type of supplements available. You also need to make sure your alkalinity stays up. If you let it fall then your calcium is not as effective.
Kent makes pretty good product. I recently switched to B-Ionic and I love it. I have seen such a difference with my coral it is not funny.
I hope this helps!
Also, Welcome to the board.
Connie