Bests & Worsts Reviews from Amazon

When I first got this filter, it made an AMAZING difference in my 20-gallon tank, turning the water crystal clear within just a few hours. But after a few weeks, the water started to go a bit yellowish again and the filter flow had slowed down to a trickle, even when I cleaned it. After a couple of months, it didn't seem very effective at all, and I went to my local fish store to look at new filters. The guy at the store asked if I was using the circular white "polishing" filter pad that came with the Eheim. I said I was, and he told me that the white pad should only be used if you're the kind of tank-obsessed person who cleans the filter every few days. Otherwise, because it's so fine, it gets clogged up with gunk fairly quickly and restricts water flow, so that the whole filter becomes less effective after a few days. He suggested removing the white pad and adding a 2nd coarse filter pad. I did that, and the filter has been working really well in the 4 months or so since. It keeps the water nice, doesn't leak, and is reasonably easy to clean. I'd give it 5 stars, except that I would have appreciated some better instructions that explained what I just mentioned above. If I hadn't encountered such an honest salesman at my local store, I would have gotten rid of it.