I just bought three packs and rotest them out. I just cleaned my filter, this past weekend and had to recharge it. It had been about 2 months, but was only slightly turing brown. Now that you mention it, I don't have the oilyness either, but I have also adjusted my phs, so that may have helped. My bioload in my 55 is 4 damsels, a red spotted scotter blenny.