Ok, I'm stumped, never seen anything like this before.
Here is the pool as I arrived. Opened by homeowner 24 hours ago. Nothing added.
CAM00033 by poolmom11, on Flickr
PH test came out pale yellow - not even registering.
TA test registered nothing. It turned a color I've never seen. FAS DPD turned pink for 15 seconds then turned clear. Ammonia test negative.
I added enough baking soda to reach 60. I poured in it front of the return in the shallow end, and before our eyes, the color change in this pic happened...
CAM00034 by poolmom11, on Flickr
I added 2 lbs of Borax. Whole pool turns blue, all yellow gone. PH test a little bit later turns a neon purple color. I didn't understand how I could overshoot with 2 lbs! For kicks I pour a small amount of Muratic Acid in the water and the original yellow color started to return. I added more baking soda and that stopped.
The TA test is now the Blue/Yellow combo we see at high chlorine levels. But none has been added! At this point I pour in a gallon of 12.5%. FAS-DPD test does the same thing.... turns pink then clear on its own. If I add drops, then the drops for the CC test, it turns a cloudy brown. What the heck?!
I had to leave cuz I work my night job at 5:30 but I'm stumped, told them I would be back on sunday. At least the pool is a pale greenish blue.