The pills is referring to Ultracarbon manufactured by Merck
http://www.consumerhealthcare.com.sg...tracarbon.html
According to website it is activated carbon
Yes, it break down to powder as mention by Barracuda
I am using overhead filter on my tank with magic clean on top layer
Magic clean are change during weekly water change
Was thinking maybe drop the pills (quantity by trial and error) with each water change.
The breakdown carbon powder will probably get trap by the magic clean, so changing the magic clean should effectively removed the carbon at the end of each week.
If this is workable, that means water condition should improved alot since activated carbon removed toxic and polish the water