Hello guys .sorry for my bad English. I have a problem I have never met before .despite working some years in pools .went to a clients pool that was working with chlorine salt generator for some time until last year. It broke and waits replace. This area has a hard water with ph goes high if you doin maintenance and since i was sure he never test ph and he propably didnt kbow swg affect ph . I asked him and i was right . The pool is with overflow tank . And has a sand filter with very old sand i told him to replace. he told me that every year he emptys the pool for the winter and when he first adds water he add only a little for the pump can suck for the bottom and push in the return jets for some time so they get clear . That was nice from him i did thw same . Return jets seem very clear. And then he fill the pool and i go there to start maintenance . I test ph about 8.0 ( always testing only with weekly calibrated electode ) and u add ph minus .goin 2 days later and ph is at 7.2 , i assume for sometime i went little lower . And i saw some small brown hard flakes comin our of some return jets . I vaccumed went the next day same thing was haplening was there vaccuming for 1 hour . Changed the valve to recirculate to be sure it isnt inside inside filter and it wasnt . I managed in a small depth side of the pool to anscrew completelt one return jet and boom huge and small piexes where xoming out as crazy .i was 3 hours rhere already closed the return jet and left . He told me it still comes out little pieces of jets . What is goin on guys .? He told me thay its the first time he see this in his pool . I asuume that it happend it was the first time someone brought ph pools down ..so it started brake all that thing . I believe pipes is full of calcium . But why ? I have visited pools in same areas that had never foxed ph and i have bever seen such a thing . Can it be from swg ? Usually from swg is white flakes not brown . I can describe it as brown egg shell pieces . What can i do to solve this and stop popin out of the pool? Bring ph lower and leave it there ? I cant imagine poppin out all the summer vacuming and then same again .ill try to upload photos .thank you 
