Alkalinity through the roof!

[denanbob]

I am trying to open our pool and it started with a black mud bath filled with millions of leaves. Right now it is brownish/green and we can see the bottom (barely, but it's there). Still lots of leaves on the bottom. I've always had trouble controlling the high alkalinity, but the number I got this afternoon is astronomical ~ 550!!!!!!!!????????????? My chlorine is up over 40ppm (trying to clear black pool), the PH is 7.1. Could anything be affecting the TA reading? When I filled the vial to 25mL and added the drops, it turned a dark midnight blue color. It took 55 drops of the titrant to change it to a maroonish/purple color. Last year, the color started out green and would change to a tan/bone color (never red like they said). Any ideas????? Could it REALLY be 550???????????

[chem geek]

As described here, "High halogen level may change indicator reaction from green/red to blue/yellow; to prevent, add thiosulfate prior to testing." You went from blue to purple which doesn't sound so good. Try first adding more R-0007 reagent (thiosulfate) to see if that helps.

Richard