Strange Difference in Bromine Decay - Bleach vs 1-Step Dichlor

[mscdman]

I’ve got some interesting data/test results I’ll be sharing soon but have been noticing some odd things on my new tub. 
 

Background:  seeded 15-30pm bromide salts.   No floater.   Oxidizer. Tub used every other day. Ah sum purged prior to fill ~1 month ago. 
 

started adding 2tsp of 1-step (85% dichlor and 15% bromide) after every use.  Findings per previous posts and steps were that after use it would raise the bromine to about 10-12ppm.  I’d skip a day and when using the day after the skip the bromine was about 4ish when I’d use it.   So about an 4ish ppm drop/day.  Anyway I continued this way for a few weeks - with CYA being added as a byproduct and after testing CYA for about 3 weeks -  CYA in the normal range.  
 

This week I’ve switched to bleach 7.5% concentrate.   Adding ~3oz (which is oddly more than should be needed per pool calculator) after each use is bringing bromine up to 10-12ppm (as it was with the 2tsp of 1-step) (FYI - I should only be needing 2.1oz of 7.5% bleach to achieve this bromine level- maybe the 1 month of CYA levels is hampering this?) 

anyway ....here’s the odd thing.   When using the 1-step above after the skipped day it was still at 4ppm.   Now after switching to bleach with a level of 10-12ppm after use, when coming back after the skipped day the bromine is 0.   
 

why would this be different using the 1-step vs bleach?

@dlleno@chem geek