man i live on a farm and we keep gold fish and koi in water truoghs to reduce algy and for somthing to do i geuss but i was just gunna ask about this because i have some red belly pirahnas that are out growing there tank and im just wondering about this leeching zink thing does anyone know details on this subject i have sevral large troughs that have been siting outside for alot longer than a year please fill me in