after a couple of years fighting algae and water quality issues. I have finally broke down and installed a new ro-di system. the system works great. really easy to install and get operational. after mixing a couple of barrels of salt water I noticed one thing. when I use to mix my water I used 8 scoops of salt to X (line on mixing drum) amount of water. same line for 18 months. now when I mix water I use 9 scoops. I'm not complaining about using more salt. I'm just confused and wondering why the additional cup needed to mix the same amount of water.