As my setup matures and I get more experience I am beginning to look ahead to what's next. I have been looking into inexpensive methods of dosing Calcium. I like some of the setups I have seen on the last tank tour and am contemplating some adjustments to meet my setup. I have a 5gal container I use to top-off my system (90gal display and 20gal sump) it is located under the tank next to the sump. I have a JBJ ATO that controls my aqualifter pump to top-off the sump. Here is my question, if and/or when I need to start adding calcium (not needed at this time) can I just add it (mrs wages) to my 5 gal ro/di topoff water and use that diluted mix (depending on calcium level in Display tank and amount of top-off). I have read that some people use distilled vinegar (about 15ml of 5% in a gal of ro/di) and two teaspoons of mrs wages, mix then dilute with ro/di and add to the sump as topoff water. I am trying to find the link for this that explains it better. But, my thinking is using the vinegar water to mix the mrs wages then dilute in my normal top-off water and if I don't have any parcipitate will it work. I currently replace about 1 gal water per day into my sump. thoughts?