Both the Emperor and Penguin filters are great I currently use both. Although the Emperor is a bit better but not for small tanks. Easy maint., I rinse off the cartridges in my kitchen sink and reuse them for 2-3 months (super cheap). In the extra media basket you can put chemical filtration like carbon or zeolite, or more bio media like Seachem's Matrix rocks or lava rock. So lots of options, the spray bars do need to be cleaned every couple of months but not very hard. The spray bars help oxygenate the water so you don't need an airstone. Both of my Emperor's do a great job, I have a Emp 400 on a 40 gal turtle tank and an Emp 280 on a 55 gal hex. with tetras, cory's, and guppies. Turtles are very messy and my tank is crystal clear and healthy water(ph, nitrates, ammonia, etc.) I love them. The one complaint I have heard others say is that it is noisy. With mine as long as you keep the water level up high and make sure the "grey flow control knob thing" is on full force or close to it, it runs silent. Maybe if you put your ear up to it and everything in your house is silent you could hear a slight hum. If you put the "knob thing" on 50% or lower it makes a bunch of noise, but good for feeding maybe. Just my 2 cents, but you should definitely carry them at the store. You co-worker doesn't have to use them, but many ppl find them very reliable and cost effective over expensive cannisters.