So here's the deal. I use two Emperor 400 power filters on my 125gal along with a UV sterilizer. These three pump a total of 1035 GPH and for years I've rarely had water problems. I've been reading lately about how carbon filtration is such a big no no and I'd love to give not using it a shot. These filters (the E400's) use a prepackaged carbon cartridge. (Marineland Rite-Size E) I've cut away pieces on the back before to remove the carbon but without them the unit looses it's strength and bows, thus dislodging itself from the guides that hold it in place. I'd be willing to ditch them entirely and perhaps use a piece of spounge type media cut to the appropiate shape and size. However, I really don't want to risk loosing filter efficiency OR god forbid have the thing get full of waste and start spilling tank water over and out the top some night while I'm sleeping! That's highly unlikely but it would suck. More likely is that when they do get to congested and the water just dumps back over the intake. Anyway, I will award a big THANK YOU to whoever comes up with the best solution with extra Brownie points for being feasible and cheap!

Carbon is used to remove impurities from the water. It's normally used after medicating a tank. Everybody has their own opinion on whether carbon should be in the filter all the time. My personal point of view is no, you don't need it. Carbon filtration can actually cause more damage than good if you forget to change it. If you change it every few weeks, then you're okay. But like I said, it's normally used after medicating a tank. I have read that people say it keeps their tank cleaner. I did challenge on person when they said their tank smelt very clean. A tank shouldn't smell clean, it should smell like a living environment.

I smile at your comment because I used to obsess over the clarity and "cleanliness" of my water, changing 80% of the water every two days or so which was insane in hindsight. Now I change every week 20%, let the plants float on the top without care, and allow algae to grow on sides except the front -- and really, the more tiny "stuff" floating in the water the better. The oscars seem to love it. They look healthy, the scales and fins are impeccable, they're growing, and they seem happy.

I have a totally carbonless tank and it's very clean. NOT FOR THE FIRST TWO MONTHS THOUGH--use carbon at least two months until your bacteria flora is well establshed in your filters..even the back and sides of your tank (I let algae grow on the back). My 125 gallon tank is combonless now and with regular sweeping out of poo (at least once a week, sometimes twice) the water is extremely clean. I do not use gravel though. It just helps clean out all the poo quicker. My fish is perfectly happy without gravel. I do have good biological filters to compensate though.