Quote Originally Posted by MrApathetic
Hi again

I have an 18x36 vinyl pool. I'm using Sodium Hypochlorite (HTH) for shock. My PH is now very high( can't be a correct reading), which makes no sense as Sod Hypo usually lowers PH when you shock. I shocked with about 10 cups, which again is high, but I've done worse in the past. Usually a hard shock makes the water clarity better, but not in this case.
Sodium Hypochlorite might raise pH slighlyly, not lower it but what is most likely happening is that the phenol red indicator has converted to chlorphenol red because of the high chlorine levels. Chlorphenol red goes through the same color changes as phenol red but at much lower pH. It will turn purple at a pH of 6.8 as compared to 8.2 with phenol red! The better quality test kits such as Taylor's and the one Ben sells on the sister website www.poolsolutions.com have a chlorine neutralizer added to help minimize this interference.
I'm off the scale with CL (the test is actually an orangy red!), so can't give you a number. PH is reading wrong as well as CL is so high.

I've shutdown my pump, and hoping things will settle out. The algae (and anything else for that matter, ha ha) is killed off, just have to deal with the cloudiness.
It is difficult to get an accurate pH reading when the Cl level is very high. Let your chlorine levels drop to a more normal range and then retest your pH before making any adjustments