bleach treatment

> I only bleached the
>fussier type of plants for one minute and the hardier ones for 2 minutes
>but this time it seemed to hit them very hard. The only plant that didn't
>suffer was the red ludwigia. All other times the plants have shown very
>little, if any, distress from this. I'm wondering could the algae have
>weakened them so they were more affected? Could the conditions in the tank
>have made them more vulnerable -- such as warmer water, harder water, more
>CO2 or etc.? It's a puzzle. (And no, I did not make a mistake with the
>bleach -- one part bleach to 19 parts water, as usual.)
>in not raining (for the moment) Vancouver

I looked at the label of my household bleach.  It said 5.25% sodium
hypochlorite by weight.  Is if possible that the supply of bleach you had
was a little more concentrated?  Either because the supplier made it a
little more concentrated or because it was older and some of the water
Just another variable to consider...

(in tropical (40 deg. F  warm) South Bend)