Renew Is ideal for use in systems where phosphate released from all activated carbons poses a problem. Renew Is also less aggressive than carbon, making it well suited for reefs and planted aquaria. It is also beneficial for use in soft water aquaria where the ph-raising property of many carbons is not an asset. Renew Will remove organics and particulates in the sub-micron range; it will also help control ammonia, nitrates, and phosphates. This product is sold by volume. Cited weight is minimal weight.directions: renew Should be used in exactly the same manner as activated carbon. Use 250 ml for each 120 160 l (30 40 gallons*). Use in a filter bag only. Although renew Is clean, it is advisable to rinse before use. It lasts about the same as carbon (4 6 weeks).i250 ml / 8.5 fl. Oz. (treats 160 l (40 us gallons))