hey, ive not got mch experience, but my other half does have some, we've had the pirahnas for a while a while now, and due to them growing had to buy a new larger tank, they now have plenty of room. we should be getting some bogwood for the tank, but as ive found out it discolours the water, we were told to put a bag of carbon in one of our internal filters to keep the water clear, is that safe for my little babies and my lobster?