GE Merline Reverse Osmosis Carbon Pre Filter 1237460 The GE Merlin Carbon PreFilter 1237460 reduces bothﾠchlorine taste & odor and sedimentﾠbefore it reaches the GE Merlin Reverse Osmosis Membranes. The GE Merlin Carbon Water Filter provides protection for the GE Merlin RO Membrane Element. The GE Merlin 1237460 water filter should be changed at least every 6 months depending on your water quality and water usage.