Quote Originally Posted by cwstnsko
Since CYA is an acid, before you turn off the pump make sure you know where the undissolved CYA is going to collect and whether that location is suitable for several hours of exposure to an acidic environment.
The pH of a saturated CYA solotion is 4.8 so it is mildly acidic. IMHO, I don't think it will cause much harm.
http://www.intox.org/databank/docume...acd/cie286.htm

By comparison, Trichlor has a pH of just over 2 , vinegar is just under 3, and unpolluted rain is about 5.6.