Soft water , or no higher than medium - hard water , is best for this biotope 软水或不高于中等硬度的水是最适合生态鱼缸的。
Surface active agents - determination of stability in hard water ; german version en 12458 : 1999 表面活性材料.耐硬水稳定性的测定
Hard water has a high mineral content . most of the dissolved minerals are either calcium or magnesium 水之矿物质含量较高，其溶解性金属以钙及镁为主。
Road vehicles . cooling fluids . test methods . part 6 : measurement of compatibility with hard water 道路车辆.冷却流体.试验方法.第6部分:硬水相容性的测定
Testing of metal working fluids ; determination of the stability of emulsified metal working fluids in hard water 金属切削冷却剂的试验.硬水中乳化金属加工冷却剂稳定
Hard water contains high concentrations of minerals and other substances that may provoke allergic reaction 因为硬水中含有可能导致过敏反应的高浓度矿物质和其它物质。
They help remove tarnish and other corrosion from metals ; they also remove hard water deposits , and discoloration and corrosion from metals 它们可用于去除金属制品的污垢和锈蚀，使其恢复光泽，也可以除去硬水的水垢。
L . o . c . plus bathroom cleaner has been designed to effectively clean soap scum and other bathroom stains as well as hard water spots and lime scale 除肥皂及其他浴室污渍，包活水渍和清洁用品留下的污垢，轻轻揉擦，即可使浴室整洁明亮。
Tests indicate that emasol 520b should be used at 15 - 45 % by weight in paraffin base oil . and an excellent rust protection and hard water tolerance can be achieved Emasol 520b在极低的剂量比率即可获得优异的防锈效果与耐硬水性能；添加剂量比率愈高，其乳液则愈呈澄清与稳定。
Problems with levels of ammonia , nitrates , nitrites , hydrogen sulfate , acidity and alkalinity , lack of dissolved oxygen in the water , hard water , and abrupt changes in temperature 繁殖育苗池内水质不良，如：氨硝酸亚硝酸化合物硫化氢酸硷度溶氧不足硬水及水温剧变等。
