I have been using the 2 Little Fishies 2-part to supplement my Kalkwasser via top-off, but I would like to reduce costs where possible, and the DIY 2-part seems like the ticket. However, if I search for the recipe, I find multiple variations of it....some have a 3rd part for Mg, but I don't see the recommended raw materials around here for whatever reason, then I saw one that said use the DIY 2-part but an off-the-shelf "Balling part C" or something, then I saw a recommendation to not bother with testing Mg and I just can't figure out which way to go here. I was actually surprised that I needed to dose anything given how few corals are actually in my tank, but apparently I do.