Seeing that DMSA and ALA remove mercury via feces - is constipation a problem when chelating with them?

In other words, assuming one has constipation - will the mercury/DMSA and/or mercury/ALA compound just sit in the colon and be discarded whenever there is a bowel movement - or will it be reabsorbed over time if it sits there too long?

Assuming the second statement is true - how would one go about taking a fibre supplement. DMSA and ALA are taken every 3 hours - so would it be good to take the fibre 1-1.5 hours after dosing with the chelators? Or is it "OK" to just wait till the 3 day cycle is over and take a fibre supplement over the next 4 or 11 days before the next chelation round (in other words - how long till reabsorption?)