I have what I am told is an old polaris boost return line since it is threaded. Anyhow, there appears to be some kind of whitish residue or something coming out of the line. My other return lines do not have anything like that coming out of it. Anyhow the stuff is clouding up my pool more so than it already is. Pool service company thought it may be something wrong with the filter but that does not explain why my other return lines are ok. I have a main sand filter for which I just changed the sand last week along with a small separate side filter of some sorts. The return line in question only operates when I run through the small side filter as well. It basically only contains like some mesh filter inside the bowl. Nothing else and when you take it off it does not have any white residue in it. Any thoughts on what could be causing this? Thanks in advance.