yeah i know sacreligious on this site but here me out........looking to build a good sized bog and pond without CP's....the reason? 12 inches annual precip........hard to come up with enough water to do a good sized one with rain water as a primary source. so i plan on doing a smaller one for CP's and a larger one with water lillies, horse tails, arrowheads and the like..................anyways what headaches am i likely to run into with my hard tap water.....shouldnt be many so long as i flush it every so often instead of just toping it off right?