Hi on this pack of Julian sprungs seaweed I have they sey on the back to take out any left over seaweed before 5 hours in the tank,not sure what effect it can have if it is in for longer,I've had left overs in after a about 8 hours and. Then I take it out and my sailfin comes and eat it out my hand and he is still fine after 4 months,so I'm not sure