Bleach? "pink indicator paper" is way too vague to give a meaningful answer to this question.
PINK
Warm water and china rose petals itself.....China rose indicator is light pink
The phenolphthalein indicator is pink in basic solutions.
pink
phenolphthalien when added to an acidic solution has a colourless indicator. but shows pink colour for basic solution.
It turns from blue to pink if the solution is acid.
phenolphthalein
Pink
This is because most likely, the indicator was a PH indicator, plain water has a neutral to low Ph indicated by blue. Whereas when vining air is added it increases the acidity of the solution as indicated by the pink color.
Phenolphthalein (3,3-bis(4-hydroxyphenyl)isobenzofuran-1(3H)-one) is a pH indicator or an indicator in volumetry; the color is pink in basic solutions and is colorless in acidic solutions.
acid should be a bright pink colour when using the indicator and alkali should go a greeny colour :) hope this helped you