Thanks, if you want to see how much crap is coming out in the filter every 2 days, take a look at my post on the equipment section. That was last week, it's not quite as bad now but still a lot for 2 days. That is also post vacuuming. I guess I'll hold it at 20 and keep the brushing and vacuuming and see if that does the trick. At least now I know the exact amount the cl level is. I love that kit so far. It's like back in college chem lab.