well im half way through my flatworm extermination campain, i dosed the recommended amount and put on the carbon once i saw the flat worms floating, then whammo brown water, i had 20 litres ready so i put that in, thats about 35% of the total water volume, the skimmer went knuts and took out a little bit of the gunk, for fear of loosing al my stock i did another 20 litres and then another and i think i did another one after that too. its all a blur now, just incase im ready to do another.
remember when the buying stops the killing can too.