If you are doing regular weekly water changes, then you don't need to spend $$ on this product IMHO. Weekly water changes are going to replenish all you need for growing your corals. If you find that you have come to a point where weekly water changes aren't keeping your Ca and Alk where they need to be, then you may at that point not only want to consider dosing Ca and Alk, but also using the colors product.
My recommendation if you are using the colors product is to also buy the test kits for the major elements that the 4 pack color program contains. That way you are dosing to replenish based on actually amounts that are being used up in your tank. This way you aren't over dosing the tank and you can be confident in the fact that the tank will have the proper amount in it.
This is what I currently do. I dose that kit in my 8 channel Kamoer along with Alk, Ca, and Mg. But I test the water to make sure I am dosing the correct amounts. You can buy test kits for these major elements: Iodine, Potassium, and Iron. This has allowed me to limit my water changes to once every 6 weeks or so. But, I repeat it is important to test the water if you are not doing water changes to make sure all your levels are where they are suppose to be: Alk, Ca, Mg, I, K, F, etc.
