2006 test FC question

[THE DUDE]

So my daughter has been unable to use her tub as she was pregnant. She wanted to drain it and leave it and I told her she really can't and she would be better off leaving it full and run so it wouldn't freeze. She set the temp to 88. However, its not getting checked regularly and no one is using it. I go over and shock it with bleach and test it occasionally.  I tested it Saturday and the ph was a little high and added some down. I also shocked it with the bleach she had, 12%, BUT, its getting old.  I checked FC and kept adding bleach trying to get it up. I put in around 14 -18 oz total in 4 oz increments.I notice when I check the fc and add the 0871 after a few drops it clears but a few seconds later starts turning pink again.. Another drop it clears than does the same thing. With her test kit it is also past its date and i get a pink hue with the 003.  i let the tub set uncovered and grabbed another sample before I left. Came home and tested it with my kit still in date and the FC does the same thing, clears than pink again after a few seconds with my stirrer running.When i put in the 003 from my kit in it turns dark. i know the water needs to be purged and again no one is going to use it, but we are below freezing levels hear still. I don't understand the pink/clear issue as mine tub and all the times I tested her's before stayed clear once it did clear with the 0871. Is the CC throwing this off possibly?  Her water is surprisingly looks crystal clear and has no smell. I didn't think it would hurt so I did drop a spare nature 2 stick in a few months ago because i knew this wasn't going to be checked regularly as it should. There was no MPS used in this fill.