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					Originally Posted by sharelove
					
				 ...when I added it on Monday, it was still cloudy. Just before the water change I had done all my  tests, everything was in order. Alk was a bit low at 2.7.....
 .... I took an alk reading on thursday and it was a lot higher: 5.8 .
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   That's the part that struck me.  Still cloudy sounds like super high Alk content.  I suspect the SW or mistake on the additive caused a dramatic pH swing.
  I dug out my Holmes/Farley info on the Alk/pH relationship.  At equilibrium in normal SW, there is a set relationship between Alk and pH.  Using this relationship as a starting guide, that Alk reading of 5.8 is right off his chart, but might equate to a pH of 8.6.  Given that the system spent a few days re-equalizing, I bet it was a lot worse than that had you measured it immediately following the water change.