Used to install pools and hottubs, you do not want chlorine or bromine tabs in the strainer unless you want to replace your heater!
Chlorine reacts with the water to form hydochlorous acid long term effect is it will eat most metals.
Bromine is almost the same, can't remember what acids it forms.
Most pool chlorine also contains cyanuirc acid as a stabilizer to stop it from reacting with uv light and breaking down.
I think it would be safe for an occasional flush, long term could have expensive results. I have no proof of this last bit. I only know what happens in pools and spas not engines as far as chlorine and bromine chemistry.
OUt of curiosity anybody ever tried phosphoric acid through a cooling
One possible bonus side effect would be the conversion of iron oxide to iron phosphate? Phosphoric acid is the main component in most rust removers.