Thanks Dave and Richard. That's a relief.
The interesting thing is, I added 1/3 of 400ml, not 400 total, so the ppm should be much lower than 26 (according to Richard's calc). But after two days (with 1.5 hour of jet), I am still measuring 12+ ppm. ???
I am going to add peroxide to it today, so hopefully everything would be good. For argument's sake, it seems that I can actually reduce the corrosive/oxidizing effect of bleach by adding some dichlor. Theoretically speaking anyway?