I didn't mix with water. Soak the pump with vinegar in pail. Overnight, remove the pump rinse with water. You will observe most Ca deposit will hv gone or detach..
Get 5 liter bottle cheaper ~4 gold coin..
You can recycle used vinegar. Using filter bag and funnel to remove the dirts & residual. I kept mine more than 2 years.
Cheers and Happy Reefing..