You mix white vinegar with kalwasser before you add water to form more CO2. Which makes it easier for the kalkwasser to dissolve in your water this means you get less of that white sandy sediment
Found this info on google if want more info
"Dissolving the Kalk powder in the Vinegar first will accomplish several very good things.
First, it will get more Calcium ions (Ca++) into the solution because you are dissolving the Ca(OH)2 in an acid instead of water, and forming Calcium Acetate, which exists as a dissociated equilibrium of free Calcium ions and Acetate ions.
Second, the Acetic Acid (Vinegar) provides an equivalent of all the CO2 you need to avoid precipitating the newly-added Calcium ions as useless white Calcium Carbonate powder.
Third, after all the cool Calcium ion chemistry is over, the leftover Acetate ions from the broken-down Vinegar leaves you with free organic Carbon in the water that feeds the bacteria in your tank so that it converts more poisonous Nitrates to NO2 gas (a very good thing).
Adding Vinegar in Kalkwasser is one of the few win-win situations for reefers -- it has a great up side and I've yet to encounter a down side to doing it. I don't know why so few reefers do it -- lack of understanding of the chemistry behind it maybe -- but a lot more are starting now that some respected reef writers have discovered it and have recommended it and even written up detailed instructions for it"
If you need a ph test solution I can give you some tablets you mix with RO water that will create test solution of 7.0 I use this to make sure my probes are still good..I can bring them to the next meeting
