I recently purchased some Muriatic acid and it was yellow in color I noticed it took one and a half times the normal measure to reduce the pH by the same amount versus the clear Muriatic acid I normally get, the manufacturer was the same.
At the hardware store I normally purchase the acid from I did notice the container was dusty, on asking the assistant manager he stated that since home construction was slow in Hawaii they have been selling less. In addition I always unscrew the cap to make sure it has never been opened and I did notice the normall shiny stainless steel caping over the clear plastic cap looked mottled. Next time I will be more picky. I normally feed acid automatically but the pump is broken and the new one has yet to be installed.
On looking this up on the internet I found comments that the acid had oxidised, I am not sure if this is the case or not. Would this change in color, other than needing more to do the same job, cause any other issues such as staining? I think not but I just wanted to be sure.
The second question concerns my friend's pool who keeps his pool at about 8 ppm Chlorine (to avoid Mustard algae), 32 to 35 CyA, 575 ppm Ca, 70 ppm Alk, salt at at 3200 ppm, and a pH of 7.4 ppm. The question is that the phosphate reading is 3500 ppm approximately, if I remember reading somewhere on the net correctly (and I am probably wrong) that high chlorine readings can lead to false phosphate readings, yes or no? If this is so would it be better to dilute by adding 2 parts tap water to one part pool water so the chlorine reading is approximately 2.67, and then multiply the phosphate reading by three?
Any help would be appreciated.