You may as well have a calcium issue,and if my beer had low or not right fermentation I would not repitch that yeast. I tell people that move into my hood that 50/50 house/RO is good for stouts and porters bur RO for lighter beers. I found this out by getting a water test.....don't waste grain funds on water if you don't need to get it tested! I have the meter that came with Palmer's water testing kit and it has never failed me, has .02 accuracy and a temp read out. A 100 gram scale is a must if your using salts,I add enough for 75-100 ppm of calcium.